The RealReal, Inc. (REAL) 10-Q 10 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 01, 2020
Cover [Abstract]
Entity registrant name	TheRealReal, Inc.
Trading symbol	REAL
Entity central index key	0001573221
Current fiscal year end date	--12-31
Entity filer category	Non-accelerated Filer
Document type	10-Q
Document period end date	Sep. 30, 2020
Document fiscal year focus	2020
Document fiscal period focus	Q3
Amendment flag	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Small Business	false
Entity Interactive Data Current	Yes
Entity common stock, shares outstanding		88,577,407
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-38953
Entity Tax Identification Number	45-1234222
Entity Address, Address Line One	55 Francisco Street
Entity Address, Address Line Two	Suite 600
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94133
City Area Code	855
Local Phone Number	435-5893
Title of 12(b) Security	Common stock, $0.00001 par value
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE

Condensed Balance Sheets (Unaud

Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 343,092	$ 154,446
Short-term investments	52,156	208,811
Accounts receivable	4,559	7,779
Inventory, net	19,236	23,599
Prepaid expenses and other current assets	18,255	13,804
Total current assets	437,298	408,439
Property and equipment, net	61,944	55,831
Operating lease right-of-use assets	115,013
Other assets	2,020	2,660
Total assets	616,275	466,930
Current liabilities
Accounts payable	5,410	11,159
Accrued consignor payable	44,490	52,820
Operating lease liabilities, current portion	15,263
Other accrued and current liabilities	55,767	54,567
Total current liabilities	120,930	118,546
Operating lease liabilities, net of current portion	111,680
Convertible senior notes, net	148,057
Other noncurrent liabilities	1,300	9,456
Total liabilities	381,967	128,002
Commitments and contingencies (Note 10)
Stockholders’ equity:
Common stock, $0.00001 par value; 500,000,000 shares authorized as of September 30, 2020 and December 31, 2019; 88,532,457 and 85,872,320 shares issued and outstanding as of September 30, 2020 and December 31, 2019, respectively	1	1
Additional paid-in capital	713,195	693,426
Accumulated other comprehensive income	107	7
Accumulated deficit	(478,995)	(354,506)
Total stockholders’ equity	234,308	338,928
Total liabilities and stockholders’ equity	$ 616,275	$ 466,930

Condensed Balance Sheets (Una_2

Condensed Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.00001	$ 0.00001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	88,532,457	85,872,320
Common stock, shares, outstanding	88,532,457	85,872,320

Condensed Statements of Operati

Condensed Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue:
Total revenue	$ 78,052	$ 81,516	$ 213,681	$ 224,307
Cost of revenue:
Total cost of revenue	28,268	29,288	78,931	83,648
Gross profit	49,784	52,228	134,750	140,659
Operating expenses:
Marketing	15,186	13,390	37,747	36,838
Operations and technology	40,578	37,407	117,858	103,271
Selling, general and administrative	35,384	28,436	103,047	76,110
Total operating expenses	91,148	79,233	258,652	216,219
Loss from operations	(41,364)	(27,005)	(123,902)	(75,560)
Interest income	448	1,902	2,350	2,918
Interest expense	(2,406)	(60)	(2,810)	(572)
Other income (expense), net		(119)	(89)	(2,106)
Loss before provision for income taxes	(43,322)	(25,282)	(124,451)	(75,320)
Provision (benefit) for income taxes	(17)	(8)	38	51
Net loss	(43,305)	(25,274)	(124,489)	(75,371)
Accretion of redeemable convertible preferred stock to redemption value				(3,355)
Net loss attributable to common stockholders	$ (43,305)	$ (25,274)	$ (124,489)	$ (78,726)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.49)	$ (0.30)	$ (1.43)	$ (2.28)
Shares used to compute net loss per share attributable to common stockholders, basic and diluted	87,869,321	84,634,956	87,176,677	34,556,485
Consignment and Service Revenue
Revenue:
Total revenue	$ 64,407	$ 69,245	$ 176,570	$ 184,890
Cost of revenue:
Total cost of revenue	16,304	19,446	47,253	52,592
Direct Revenue
Revenue:
Total revenue	13,645	12,271	37,111	39,417
Cost of revenue:
Total cost of revenue	$ 11,964	$ 9,842	$ 31,678	$ 31,056

Condensed Statements of Compreh

Condensed Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (43,305)	$ (25,274)	$ (124,489)	$ (75,371)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on investments	(294)	(4)	100	26
Comprehensive loss	$ (43,599)	$ (25,278)	$ (124,389)	$ (75,345)

Condensed Statements of Redeema

Condensed Statements of Redeemable Convertible Preferred Stock, Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2018	$ (257,690)					$ (25)	$ (257,665)
Beginning balance, shares at Dec. 31, 2018		31,053,601	73,724,645
Beginning balance at Dec. 31, 2018		$ 151,381	$ 142,819
Beginning balance, shares at Dec. 31, 2018				8,593,077
Issuance of convertible preferred stock, net of issuance costs		$ 43,572
Issuance of convertible preferred stock, net of issuance costs, shares		6,350,345
Issuance of convertible preferred stock upon conversion of notes, net of issuance costs			$ 26,279
Issuance of convertible preferred stock upon conversion of notes, net of issuance costs, shares			3,831,766
Accretion of redeemable convertible preferred stock to redemption value	(3,355)	$ 3,355			$ (3,260)		(95)
Compensation expense related to stock sales by current and former employees	819				819
Issuance of common stock upon exercise of options	1,319				1,319
Issuance of common stock upon exercise of options, shares				739,053
Issuance of common stock upon exercise of warrants	13				13
Issuance of common stock upon exercise of warrants, shares				4,935
Stock-based compensation expense	1,109				1,109
Other comprehensive income (loss)	28					28
Net loss	(23,222)						(23,222)
Ending balance at Mar. 31, 2019	$ (280,979)					3	(280,982)
Ending balance, shares at Mar. 31, 2019	114,960,357	37,403,946	77,556,411
Ending balance at Mar. 31, 2019	$ 367,406	$ 198,308	$ 169,098
Ending balance, shares at Mar. 31, 2019				9,337,065
Beginning balance at Dec. 31, 2018	(257,690)					(25)	(257,665)
Beginning balance, shares at Dec. 31, 2018		31,053,601	73,724,645
Beginning balance at Dec. 31, 2018		$ 151,381	$ 142,819
Beginning balance, shares at Dec. 31, 2018				8,593,077
Net loss	(75,371)
Ending balance at Sep. 30, 2019	357,236			$ 1	690,365	1	(333,131)
Ending balance, shares at Sep. 30, 2019				85,759,021
Beginning balance at Mar. 31, 2019	$ (280,979)					3	(280,982)
Beginning balance, shares at Mar. 31, 2019	114,960,357	37,403,946	77,556,411
Beginning balance at Mar. 31, 2019	$ 367,406	$ 198,308	$ 169,098
Beginning balance, shares at Mar. 31, 2019				9,337,065
Additional issuance costs for Series H redeemable convertible preferred stock (total issuance costs of $166)		$ (80)
Reallocation of issuance costs for Series H convertible preferred stock (total issuance costs of $59)			$ 4
Issuance of common stock upon exercise of options	423			$ 1	422
Issuance of common stock upon exercise of options, shares				358,459
Issuance of common stock upon exercise of warrants	20				20
Issuance of common stock upon exercise of warrants, shares				5,742
Stock-based compensation expense	1,287				1,287
Other comprehensive income (loss)	2					2
Net loss	(26,875)						(26,875)
Ending balance at Jun. 30, 2019	(306,122)			$ 1	1,729	5	(307,857)
Ending balance, shares at Jun. 30, 2019		37,403,946	77,556,411
Ending balance at Jun. 30, 2019		$ 198,228	$ 169,102
Ending balance, shares at Jun. 30, 2019				9,701,266
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering	198,228				198,228
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering, shares		(37,403,946)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering		$ (198,228)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering, shares				19,585,426
Conversion of convertible preferred stock to common stock in connection with initial public offering	169,102				169,102
Conversion of convertible preferred stock to common stock in connection with initial public offering, shares			(77,556,411)
Conversion of convertible preferred stock to common stock in connection with initial public offering			$ (169,102)
Conversion of convertible preferred stock warrants to common stock warrants in connection with initial public offering	2,710				2,710
Conversion of convertible preferred stock to common stock in connection with initial public offering, shares				38,778,180
Issuance of common stock in connection with initial public offering, net of issuance costs of $5,428	315,422				315,422
Issuance of common stock in connection with initial public offering, net of issuance costs of $5,428, shares				17,250,000
Issuance of common stock upon cashless exercise of warrants, shares				89,542
Issuance of common stock upon exercise of options	674				674
Issuance of common stock upon exercise of options, shares				352,638
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes	(20)				(20)
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes, shares				1,969
Stock-based compensation expense	2,520				2,520
Other comprehensive income (loss)	(4)					(4)
Net loss	(25,274)						(25,274)
Ending balance at Sep. 30, 2019	357,236			$ 1	690,365	1	(333,131)
Ending balance, shares at Sep. 30, 2019				85,759,021
Beginning balance at Dec. 31, 2019	338,928			$ 1	693,426	7	(354,506)
Beginning balance, shares at Dec. 31, 2019				85,872,320
Issuance of common stock upon exercise of options	2,564				2,564
Issuance of common stock upon exercise of options, shares				964,085
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes	(151)				(151)
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes, shares				14,289
Stock-based compensation expense	3,410				3,410
Other comprehensive income (loss)	314					314
Net loss	(38,292)						(38,292)
Ending balance at Mar. 31, 2020	306,773			$ 1	699,249	321	(392,798)
Ending balance, shares at Mar. 31, 2020				86,850,694
Beginning balance at Dec. 31, 2019	338,928			$ 1	693,426	7	(354,506)
Beginning balance, shares at Dec. 31, 2019				85,872,320
Purchase of capped calls	(22,546)
Equity component of convertible senior notes, net of issuance costs	800
Net loss	(124,489)
Ending balance at Sep. 30, 2020	234,308			$ 1	713,195	107	(478,995)
Ending balance, shares at Sep. 30, 2020				88,532,457
Beginning balance at Mar. 31, 2020	306,773			$ 1	699,249	321	(392,798)
Beginning balance, shares at Mar. 31, 2020				86,850,694
Issuance of common stock upon exercise of options	1,790				1,790
Issuance of common stock upon exercise of options, shares				429,339
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes	(453)				(453)
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes, shares				68,208
Stock-based compensation expense	6,129				6,129
Purchase of capped calls	(22,546)				(22,546)
Equity component of convertible senior notes, net of issuance costs	19,020				19,020
Other comprehensive income (loss)	80					80
Net loss	(42,892)						(42,892)
Ending balance at Jun. 30, 2020	267,901			$ 1	703,189	401	(435,690)
Ending balance, shares at Jun. 30, 2020				87,348,241
Issuance of common stock upon exercise of options	2,781				2,781
Issuance of common stock upon exercise of options, shares				720,682
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes	(147)				(147)
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes, shares				463,534
Stock-based compensation expense	7,372				7,372
Other comprehensive income (loss)	(294)					(294)
Net loss	(43,305)						(43,305)
Ending balance at Sep. 30, 2020	$ 234,308			$ 1	$ 713,195	$ 107	$ (478,995)
Ending balance, shares at Sep. 30, 2020				88,532,457

Condensed Statements of Redee_2

Condensed Statements of Redeemable Convertible Preferred Stock, Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
Initial Public Offering
Issuance of stock, net of issuance costs		$ 5,428
Equity Component of Convertible Senior Notes
Stock issuance costs	$ 767
Series H Redeemable Convertible Preferred Stock
Stock issuance costs			$ 166	$ 86
Series H Convertible Preferred Stock
Stock issuance costs			$ 59	$ 63

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net loss	$ (124,489)	$ (75,371)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	13,673	9,537
Stock-based compensation expense	16,911	4,916
Reduction of operating lease right-of-use assets	12,003
Bad debt expense	661	1,208
Compensation expense related to stock sales by current and former employees		819
Change in fair value of convertible preferred stock warrant liability		2,100
Accretion of unconditional endowment grant liability	39	70
Accretion of debt discounts and issuance costs	1,268	11
Amortization of premiums (discounts) on short-term investments	(114)	38
Changes in operating assets and liabilities:
Accounts receivable	2,559	(2,572)
Inventory, net	4,363	(3,491)
Prepaid expenses and other current assets	(4,626)	(3,375)
Other assets	578	136
Operating lease liability	(8,710)
Accounts payable	(4,164)	1,394
Accrued consignor payable	(8,330)	4,611
Other accrued and current liabilities	2,511	494
Other noncurrent liabilities	(150)	1,356
Net cash used in operating activities	(96,017)	(58,119)
Cash flow from investing activities:
Purchases of short-term investments	(73,280)	(12,169)
Proceeds from maturities of short-term investments	222,217	33,998
Proceeds from sale of short-term investments	7,932
Capitalized proprietary software development costs	(6,640)	(6,670)
Purchases of property and equipment	(15,685)	(16,111)
Net cash provided by (used in) investing activities	134,544	(952)
Cash flow from financing activities:
Proceeds from issuance of common stock in initial public offering, net of issuance costs		315,486
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs		43,492
Proceeds from issuance of convertible preferred stock, net of issuance costs		26,283
Proceeds from issuance of convertible senior notes, net of issuance costs	166,278
Purchase of capped calls	(22,546)
Proceeds from exercise of stock options and common stock warrants	7,135	2,448
Taxes paid related to restricted stock vesting	(748)	(20)
Repayment of debt		(9,250)
Net cash provided by financing activities	150,119	378,439
Net increase in cash, cash equivalents and restricted cash	188,646	319,368
Cash, cash equivalents, and restricted cash
Beginning of period	154,446	45,627
End of period	343,092	364,995
Supplemental disclosures of cash flow information
Cash paid for interest	7	532
Cash paid for income taxes	90
Supplemental disclosures of non-cash investing and financing activities
Accretion of redeemable convertible preferred stock to redemption value		3,355
Purchases of property and equipment included in accounts payable and other accrued and current liabilities	(3,102)	(877)
Purchases of capitalized proprietary software development costs included in accounts payable and other accrued and current liabilities	501
Deferred offering costs in accounts payable and accrued liabilities		28
Conversion of convertible preferred stock warrants in connection with IPO		2,710
Issuance costs associated with issuance of convertible senior notes included in other accrued and current liabilities	469
Tax withholding liability for restricted stock	$ 3
Redeemable Convertible Preferred Stock
Supplemental disclosures of non-cash investing and financing activities
Conversion of convertible stock in connection with IPO		198,228
Convertible Preferred Stock
Supplemental disclosures of non-cash investing and financing activities
Conversion of convertible stock in connection with IPO		$ 169,102

Description of Business and Bas

Description of Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business and Basis of Presentation	Note 1. Description of Business and Basis of Presentation Organization and Description of Business The RealReal, Inc. (the “Company”) is an online marketplace for authenticated, consigned luxury goods across multiple categories, including women’s, men’s, kids’, jewelry and watches, and home and art. The Company was incorporated in the state of Delaware on March 29, 2011 and is headquartered in San Francisco, California. Impact of the Coronavirus (“COVID-19”) Pandemic The COVID-19 pandemic Operations in the Company’s fulfillment facilitates were initially limited in accordance with shelter-in-place orders resulting in operations below full capacity In-person white glove consignment appointments were temporarily suspended and augmented with virtual appointments but remain an option for our consignor base. All luxury consignment offices and retail stores were temporarily closed for varying periods of time but were all open during the entirety of three months ended September 30, 2020. While the continuing and ultimate impact of the COVID-19 pandemic is highly uncertain, the Company expects its business operations and results of operations, including its net revenues, earnings and cash flows, will be further materially adversely impacted, including as a result of possible new restrictions to curb the spread of the disease, decreased productivity due to shelter-in-place orders, and a slowdown in the U.S. economy and uncertain global economic outlook. The Company believes that its financial resources, along with managing discretionary expenses, will allow it to manage the anticipated impact of COVID-19 on the Company’s business operations for the foreseeable future. The Company believes its existing cash and cash equivalents and short-term investments as of September 30, 2020 will be sufficient to meet its working capital and capital expenditures needs for at least the next 12 months. Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and the requirements of the U.S. Securities and Exchange Commission (the “SEC”) for interim reporting. The Company’s functional and reporting currency is the U.S. dollar. The condensed balance sheet as of December 31, 2019 included herein was derived from the audited financial statements as of that date. The accompanying unaudited condensed financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to state fairly the Company’s financial position, results of operations, comprehensive loss, redeemable convertible preferred stock, convertible preferred stock, and stockholders’ equity (deficit), and cash flows for the periods presented. These unaudited condensed financial statements should be read in conjunction with the Company’s financial statements and notes included in our Annual Report on Form 10-K filed with the SEC on March 11, 2020. Initial Public Offering The Company’s registration statement on Form S-1 (the “IPO Registration Statement”) related to its initial public offering (“IPO”) was declared effective on June 27, 2019, and the Company’s common stock began trading on the Nasdaq Global Select Market on June 28, 2019. On July 2, 2019, the Company completed its IPO, selling 15,000,000 shares of common stock at a price to the public of $20.00 per share, plus an additional 2,250,000 shares of common stock at a price to the public of $20.00 per share pursuant to the exercise of the underwriters’ option to purchase additional shares. The Company received aggregate net proceeds of $315.5 million after deducting underwriting discounts and commissions of $24.1 million and issuance costs of $5.3 million. Immediately p rior to the completion of the IPO, the Company filed its Amended and Restated Certificate of Incorporation, which authorizes a total of 500,000,000 shares of common stock, and 50,000,000 shares of undesignated preferred stock The Company recorded the conversion of 114,960,357 shares of convertible preferred stock and redeemable convertible preferred stock then outstanding into 58,363,606 shares of common stock to additional paid-in capital. All outstanding preferred stock warrants converted into an aggregate of 103,563 common stock warrants Reverse Stock Split On June 13, 2019 the Company effected a reverse split of shares of the Company’s common stock on a 1-for-2 basis (the “Reverse Stock Split”). All issued and outstanding shares of common stock, warrants for common stock, options to purchase common stock and the related per share amounts contained in the financial statements have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. The par value and authorized shares of common stock were not adjusted as a result of the Reverse Stock Split. Additionally, the authorized, issued and outstanding shares of redeemable convertible preferred stock and convertible preferred stock and their related per share amounts, other than the conversion price per share, were not adjusted as a result of the Reverse Stock Split.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of expenses during the reporting period. Significant items subject to such estimates and assumptions include those related to revenue recognition, including the returns reserve and material right related to the Company’s tiered consignor commission plan, valuation of inventory, software development costs, stock-based compensation, redemption value of redeemable convertible preferred stock, incremental borrowing rates related to lease liability, fair value of the liability component of convertible senior notes, and other contingencies. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates. The Company assessed the impacts of the pandemic on the estimates and assumptions used in preparing these financial statements. In particular, the Company is monitoring its returns reserve and adjusting in response to changing consumer behaviors. Its estimates may change as new events occur and additional information is obtained; any such changes will be recognized in the financial statements. Actual results could differ from estimates, and any such differences may be material to the financial statements. Net Loss per Share Attributable to Common Stockholders The Company follows the two-class method when computing net loss per common share when shares are issued that meet the definition of participating securities. The two-class method determines net loss per common share for each class of common stock and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income (loss) available or attributable to common stockholders for the period to be allocated between common stock and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. Before the IPO, the Company’s redeemable convertible preferred stock and convertible preferred stock were considered participating securities. However, the holders of such shares did not have a contractual obligation to participate in the Company’s losses. The Company’s convertible senior notes are participating securities as they give the holders the right to receive dividends if dividend or distribution declared to the common stockholders is equal to or greater than the last reported sale price of the Company’s common stock on the trading day immediately preceding the ex-dividend date for such dividend or distribution No . For periods in which the Company reports net losses, diluted net loss per common share attributable to common stockholders is the same as basic net loss per common share attributable to common stockholders, because potentially dilutive common shares and assumed conversion of the convertible senior notes are not assumed to have been issued within the calculation, if their effect is anti-dilutive. Revenue Recognition The Company generates revenue from the sale of pre-owned luxury goods through its online marketplace and retail locations. Consignment and Service Revenue The Company provides a service to sell pre-owned luxury goods on behalf of consignors to buyers through its online marketplace and retail locations. The Company retains a percentage of the proceeds received as payment for its consignment service, which the Company refers to as its take rate. The Company reports consignment revenue on a net basis as an agent and not the gross amount collected from the buyer. Title to the consigned goods remain with the consignor until transferred to the buyer subsequent to purchase of the consigned goods and expiration of the allotted return period. The Company does not take title of consigned goods at any time except in certain cases where returned goods become Company-owned inventory. The Company recognizes consignment revenue upon purchase of the consigned good by the buyer as its performance obligation of providing consignment services to the consignor is satisfied at that point. Consignment revenue is recognized net of certain buyer incentives and estimated returns and cancellations. The Company recognizes a returns reserve based on historical experience, which is recorded in other accrued and current liabilities on the condensed balance sheets (see Note 5). Sales tax assessed by governmental authorities is excluded from revenue. Certain transactions provide consignors with a material right resulting from the tiered consignor commission plan. Under this plan, the amount an individual consignor receives for future sales of consigned goods may be dependent on previous consignment sales for that consignor within his/her consignment period. Accordingly, in certain consignment transactions, a small portion of the Company’s consignment revenue is allocated to such material right using the portfolio method and recorded as deferred revenue, which is recorded in other accrued and current liabilities on the condensed balance sheets. The Company charges shipping fees to buyers and has elected to treat shipping and handling activities performed after control transfers to the buyer as fulfillment activities. All outbound shipping and handling costs are accounted for as fulfillment costs in cost of consignment and service revenue at the time revenue is recognized. The Company also generates subscription revenue from monthly memberships allowing buyers early access to shop for luxury goods. The buyers receive the early access and other benefits over the term of the subscription period, which represents a single stand-ready performance obligation. Therefore, the subscription fees paid by the buyer are recognized over the monthly subscription period. Subscription revenue was not material in the three months and nine months ended September 30, 2020 and 2019. Direct Revenue The Company generates direct revenue from the sale of Company-owned inventory. The Company recognizes direct revenue on a gross basis upon shipment of the purchased good to the buyer as the Company acts as the principal in the transaction. Direct revenue is recognized net of incentives and estimated returns. Sales tax assessed by governmental authorities is excluded from revenue. Cost of direct revenue is also recognized upon shipment to the buyer in an amount equal to that paid to the consignor from the original consignment sale, an amount equal to that paid as a direct purchase from a third party, or the lower of cost of the inventory purchased and its net realizable value. Incentives Promotional incentives, which include basket promotional code discounts and other credits, may periodically be offered to consignors and buyers. These are treated as a reduction of consignment and service revenue and direct revenue. Additionally, the Company may offer site credits to buyers on current transactions to be applied towards future transactions, which are accounted as deferred revenue and included in other accrued and current liabilities on the condensed balance sheets. Contract Liabilities The Company’s contractual liabilities consist of deferred revenue for material rights primarily related to the tiered consignor commission plan totaling $1.3 million as of September 30, 2020 and Cost of Revenue Cost of consignment and service revenue consist of shipping costs, credit card fees, packaging, customer service personnel-related costs, and website hosting services. Cost of direct revenue consists of the cost of goods sold, credit card fees, packaging, customer service personnel-related costs, and website hosting services. Stock-based Compensation Stock-based compensation expense related to employees is measured based on the grant-date fair value of the awards. Compensation expense is recognized in the statements of operations over the period during which the employee is required to perform services in exchange for the award (the vesting period of the applicable award) using the straight-line method. The Company estimates the fair value of stock options granted using the Black-Scholes option pricing model and accounts for forfeitures as they occur. The fair value of restricted stock units (“RSUs”) is estimated based on the fair market value of the Company’s common stock on the date of grant, which is determined based on the closing price of the Company’s common stock. Prior to the IPO, certain employees have sold their shares of the Company’s common stock to the Company’s existing investors. In such secondary sale transactions, the Company recorded the difference in purchase price and the fair value of such shares as compensation expense within selling, general and administrative in the statements of operations and a corresponding credit to additional paid-in capital. Cash, Cash Equivalents The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents consist primarily of amounts invested in U.S. treasury securities. Short-term Investments The Company has classified and accounted for its short-term investments as available-for-sale which are carried at fair value on its condensed balance sheets. Available-for-sale securities with remaining maturities of 12 months or less are classified as short term and available-for-sale securities with remaining maturities greater than 12 months are classified as long term. The Company evaluates its short-term investments periodically for possible impairment. A decline in the fair value below the amortized costs of the short-term investment is considered an other-than-temporary impairment if the Company has the intent to sell the short-term investments or it is more likely than not that the Company will be required to sell the short-term investment before recovery of the entire amortized cost basis. Inventory, Net Inventory primarily consists of finished goods arising from goods returned after the title has transferred from the buyer to the Company in an amount equal to that paid to the consignor. The Company also periodically purchases finished goods directly from vendors. Inventory is valued at the lower of cost and net realizable value using the specific identification method and the Company records provisions, as appropriate, to write down obsolete and excess inventory to estimated net realizable value. After the inventory value is reduced, adjustments are not made to increase it from the estimated net realizable value. Our provisions to write down obsolete and excess inventory to net realizable value have not been material as of September 30, 2020 and December 31, 2019. Software Development Costs Proprietary software includes the costs of developing the Company’s internal proprietary business platform and automation projects. The Company capitalizes qualifying proprietary software development costs that are incurred during the application development stage. Capitalization of costs begins when two criteria are met: (1) the preliminary project stage is completed and (2) it is probable that the software will be completed and used for its intended function. Such costs are capitalized in the period incurred. Capitalization ceases and amortization begins when the software is substantially complete and ready for its intended use, including the completion of all significant testing. Costs related to preliminary project activities and post-implementation operating activities are expensed as incurred. Accretion of Redeemable Convertible Preferred Stock The carrying value of the redeemable convertible preferred stock that is probable of redemption is accreted to redemption value from the date of issuance to the earliest redemption date using the effective interest method until redemption is no longer probable. Increases to the carrying value of redeemable convertible preferred stock recognized in each period are charged to additional paid-in capital, or in the absence of additional paid-in capital, charged to accumulated deficit. Convertible Preferred Stock Warrant Liability The Company issued convertible preferred stock warrants in conjunction with the issuance of debt. Such warrants were recorded as other noncurrent liabilities on the condensed balance sheets at their estimated fair value because the shares underlying the warrants may obligate the Company to transfer assets to the holders at a future date under certain circumstances such as a deemed liquidation event. The warrants are subject to re-measurement at each balance sheet date and the change in fair value, if any, is included in other income (expense), net. The Company continued to remeasure these warrants until the earlier of the expiration, exercise or conversion of the convertible preferred stock warrants into common warrants, which occurred upon the completion of the IPO on July 2, 2019. In connection with the completion of the IPO, the convertible preferred stock warrants automatically converted into common stock warrants. Upon conversion of the convertible preferred stock warrants, the related convertible preferred stock warrant liability was reclassified to additional paid-in capital. Leases Prior to the adoption of ASC 842 on January 1, 2020 Leases are reviewed for classification as operating or capital leases. For operating leases, the Company recognizes rent on a straight-line basis over the term of the lease. The Company records the difference between cash payments and rent expense recognized as a deferred rent liability included in other accrued and current liabilities and other noncurrent liabilities on the condensed balance sheets. Incentives granted under the Company’s facility leases, including allowances to fund leasehold improvements, are deferred and are recognized as adjustments to rental expense on a straight-line basis over the term of the lease. Subsequent to the adoption of ASC 842 on January 1, 2020 Contracts that have been determined to convey the right to use an identified asset are evaluated for classification as an operating or finance lease. For the Company’s operating leases, the Company records a lease liability based on the present value of the lease payments at lease inception, using the applicable incremental borrowing rate. The Company estimates the incremental borrowing rate by developing its own synthetic credit rating, corresponding yield curve, and the terms of each lease at the lease commencement date The Company has elected the practical expedients that allows for the combination of lease components and non-lease components and to record short-term leases as lease expense on a straight-line basis on the condensed statements of operations. Variable lease payments are recorded as expense as they are incurred. The Company has finance leases for several vehicles, and the amounts of finance lease right-of-use assets and finance lease liabilities have been immaterial to date. Convertible Senior Notes In accordance with ASC 470, convertible debt instruments that may be settled in cash or other assets, or partially in cash, upon conversion, are separately accounted for as long-term debt and equity components (or conversion feature). The accounting applies to the Company’s convertible senior notes (the “Notes”) Capped Call Transactions In June 2020, in connection with the issuance of its convertible senior notes, the Company entered into Capped Call Transactions (see Note 6). The Capped Call Transactions are expected generally to reduce the potential dilution to the holders of the Company’s common stock upon any conversion of the Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of converted Notes, with such reduction and/or offset subject to a cap based on the cap price. The capped calls meet the conditions outlined in ASC 815-40, Derivatives and Hedging Debt Issuance Costs Debt issuance costs are amortized to interest expense over the estimated life of the related debt based on the effective interest method. In accordance with ASC 835, Interest Concentrations of Credit Risks Financial instruments that potentially subject the Company to concentrations of credit risk consist of cash and cash equivalents, accounts receivable, and investments. At times, such amount may exceed federally-insured limits. The Company reduces credit risk by placing its cash, cash equivalents, and investments with major financial institutions within the United States. As of September 30, 2020 and December 31, 2019, there were no customers that represented 10% or more of the Company’s accounts receivable balance and there were no customers that individually exceeded 10% of the Company’s total revenue for each of the three and nine months ended September 30, 2020 and 2019. Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) The Company is an emerging growth company “EGC”, as defined in the Jumpstart Our Business Startups Act of 2012 (JOBS Act). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The new standard is effective for the Company beginning January 1, 2022. The Company chose to early adopt the standard on January 1, 2020. The Company can choose to adopt new or revised accounting standards earlier than such time those standards apply to private companies and retain its election for the extended transition period, if early adoption is permitted for all entities. The Company adopted and began applying the standard on January 1, 2020 using the modified retrospective approach and applied it to all existing leases as of the adoption date, which allows for a cumulative-effect adjustment to retained earnings on the adoption date. The Company will continue to present prior period amounts under ASC 840. In addition, the Company elected the package of practical expedients permitted under the transition guidance within the new standard which does not require the Company to reassess whether contracts that expired prior to the adoption date contained an embedded lease, reassess historical lease classification, or evaluate direct costs for leases that were in effect at the adoption date. As a result of implementing this guidance, the Company recognized $110.3 million in right of use assets as of January 1, 2020. The Company also recorded $12.8 million in current operating lease liabilities and $106.2 million in operating lease liabilities, net of current portion in its condensed balance sheet as of January 1, 2020. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820) Recently Issued Accounting Pronouncements As an EGC, the Company has elected to retain the ability to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that the Company (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opt out of the extended transition period provided in the JOBS Act. As a result, the Company’s financial statements may not be comparable to companies that comply with new or revised accounting pronouncements as of public company effective dates. Because the market value of the Company’s common stock held by non-affiliates exceeded $700 million as of June 30, 2020, the Company will be deemed a “large accelerated filer” under the Exchange Act and will lose emerging growth company status as of December 31, 2020. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments (Topic 326) As an EGC, the Company has not yet adopted the standard. However, the Company will be required to adopt the standard as of January 1, 2020 in its 2020 10-K. The Company does not expect the adoption of this standard to have a material impact on the operating results. In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718), In August 2020, the FASB issued ASU 2020-06, Debt – Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity which simplifies accounting for convertible instruments by removing major separation models required under current U.S. GAAP. ASU 2020-06 removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and it also simplifies the diluted earnings per share calculation in certain areas.

Cash, Cash Equivalents and Shor

Cash, Cash Equivalents and Short-term Investments	9 Months Ended
	Sep. 30, 2020
Cash And Cash Equivalents [Abstract]
Cash, Cash Equivalents, and Short-term Investments	Note 3. Cash, Cash Equivalents and Short-term Investments The following tables summarize the estimated value of the Company’s cash, cash equivalents and short-term investments (in thousands): September 30, 2020 Amortized Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 191,279 $ — $ — $ 191,279 Money market fund 151,813 — — 151,813 Total cash and cash equivalents $ 343,092 $ — $ — $ 343,092 Short-term investments: U.S. Treasury securities $ 16,015 $ 40 $ — $ 16,055 Corporate bonds 36,034 67 — 36,101 Total short-term investments $ 52,049 $ 107 $ — $ 52,156 December 31, 2019 Amortized Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 111,319 $ — $ — $ 111,319 U.S. Treasury securities 29,981 — — 29,981 Money market fund 5,399 — — 5,399 Corporate bonds 3,749 — — 3,749 Agency bonds 2,000 — — 2,000 Commercial paper 1,998 — — 1,998 Total cash and cash equivalents $ 154,446 $ — $ — $ 154,446 Short-term investments: U.S. Treasury securities $ 151,857 $ 13 $ — $ 151,870 Corporate bonds 38,149 — (5 ) 38,144 Agency bonds 11,028 — (2 ) 11,026 Commercial paper 7,770 1 — 7,771 Total short-term investments $ 208,804 $ 14 $ (7 ) $ 208,811 As of September 30, 2020 and December 31, 2019, the contractual maturity for the short-term investments is less than one year. For the three and nine months ended September 30, 2020 and 2019, the Company recognized no material realized gains or losses on short-term investments.

Fair Value Measurement

Fair Value Measurement	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurement	Note 4. Fair Value Measurement Assets and liabilities recorded at fair value on a recurring basis on the condensed balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. There were no transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy during the periods presented. The following tables provide the financial instruments measured at fair value (in thousands): September 30, 2020 Level 1 Level 2 Level 3 Total Assets Cash equivalents: Money market fund $ 151,813 $ — $ — $ 151,813 Total cash equivalents $ 151,813 $ — $ — $ 151,813 Short-term investments: U.S. Treasury securities $ 16,055 $ — $ — $ 16,055 Corporate bonds — 36,101 — 36,101 Total short-term investments $ 16,055 $ 36,101 $ — $ 52,156 December 31, 2019 Level 1 Level 2 Level 3 Total Assets Cash equivalents: U.S. Treasury securities $ 29,981 $ — $ — $ 29,981 Money market fund 5,399 — — 5,399 Corporate bonds — 3,749 — 3,749 Agency bonds — 2,000 — 2,000 Commercial paper — 1,998 — 1,998 Total cash equivalents $ 35,380 $ 7,747 $ — $ 43,127 Short-term investments: U.S. Treasury securities $ 151,870 $ — $ — $ 151,870 Corporate bonds — 38,144 — 38,144 Agency bonds — 11,026 — 11,026 Commercial paper — 7,771 — 7,771 Total short-term investments $ 151,870 $ 56,941 $ — $ 208,811 On June 15, 2020, the Company issued 3.00% convertible senior notes due 2025 with embedded conversion features. The Company estimated the fair value of the Notes using a discounted cash flow approach to derive the value of a debt instrument using the expected cash flows and the estimated yield related to the convertible notes. The significant assumptions used in estimating the expected cash flows were the estimated market yield based on an implied yield and credit quality analysis of a term loan with similar attributes. The Company recorded approximately $152.7 million as the fair value of the liability on June 15, 2020, with a corresponding amount recorded as a discount on the initial issuance of the Notes of approximately $19.8 million. The debt discount was recorded to equity and is being amortized to the debt liability over the life of the Notes using the effective interest method. As of September 30, 2020, the fair value of the Notes, which differs from its carrying value is determined by prices for the Notes observed in market trading. The market for trading of the Notes is not considered to be an active market and therefore the estimate of fair value is based on Level 2 inputs, such as interest rates. As of September 30, 2020, the estimated fair value of the Notes, which has an aggregate face value of $172.5 million, was $172.0 million based on the market price on the last trading day for the period.

Condensed Balance Sheet Compone

Condensed Balance Sheet Components	9 Months Ended
	Sep. 30, 2020
Balance Sheet Related Disclosures [Abstract]
Condensed Balance Sheet Components	Note 5. Condensed Balance Sheet Components Property and Equipment, Net Property and equipment, net is recorded at cost less accumulated depreciation and amortization. Depreciation and amortization are recorded on a straight-line basis over the estimated useful lives of the respective assets. Property and equipment, net consists of the following (in thousands): September 30, 2020 December 31, 2019 Proprietary software $ 23,288 $ 23,318 Furniture and equipment 25,742 21,083 Automobiles 667 718 Leasehold improvements 50,852 43,505 100,549 88,624 Less: accumulated depreciation and amortization (38,605 ) (32,793 ) Property and equipment, net $ 61,944 $ 55,831 Depreciation and amortization expense on property and equipment was $4.9 million and $3.5 million for the three months ended September 30, 2020 and 2019, respectively, and $13.7 million and $9.5 million for the nine months ended September 30, 2020 and 2019, respectively. Proprietary software taken out of service during the three months ended September 30, 2020 was $6.8 million and was fully depreciated. Other Accrued and Current Liabilities Other accrued and current liabilities consist of the following (in thousands): September 30, 2020 December 31, 2019 Returns reserve $ 12,793 $ 17,005 Accrued compensation 14,043 11,626 Site credit liability 5,439 5,080 Accrued sales tax and other taxes 5,446 6,132 Deferred revenue 1,960 4,767 Accrued marketing and outside services 10,297 6,830 Accrued interest 1,496 — Other 4,293 3,127 Other accrued and current liabilities $ 55,767 $ 54,567

Debt and Convertible Preferred

Debt and Convertible Preferred Stock Warrants	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Debt and Convertible Preferred Stock Warrants	Note 6. Debt and Convertible Preferred Stock Warrants Convertible Senior Notes In June 2020, the Company issued an aggregate principal of $172.5 million of its 3.00% Convertible Senior Notes due 2025 (the “Notes”), pursuant to an indenture (the “Indenture”) between the Company and U.S. Bank National Association, as trustee, in a private offering (the “Note Offering”) to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended (the “Securities Act”). The Notes issued in the Note Offering include $22.5 million in aggregate principal amount of the Notes sold to the initial purchasers resulting from the exercise in full of their option to purchase additional Notes. The Notes will mature on June 15, 2025, unless earlier redeemed or repurchased by the Company or converted. The Company received net proceeds from the Notes offering of approximately $165.8 million, after deducting the initial purchasers’ discount and commission and offering expenses. The Company used approximately $22.5 million of the net proceeds from the Notes offering to fund the net cost of entering into the capped call transactions described below. The Company intends to use the remainder of the net proceeds for general corporate purposes. The Notes accrue interest at a rate of 3.00% per annum, payable semi-annually in arrears on June 15 and December 15 of each year, beginning on December 15, 2020. The initial conversion rate applicable to the Notes is 56.2635 shares of common stock per $1,000 principal amount of Notes (which is equivalent to an initial conversion price of approximately $17.77 per share of the Company’s common stock). The conversion rate is subject to adjustment upon the occurrence of certain specified events but will not be adjusted for accrued and unpaid interest. In addition, upon the occurrence of a corporate event, the Company will, in certain circumstances, increase the conversion rate by a number of additional shares for a holder that elects to convert its Notes in connection with such corporate event. The Notes will be redeemable, in whole or in part, at the Company’s option at any time, and from time to time, on or after June 20, 2023 if the last reported sale price per share of the Company’s common stock exceeds 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive), including the trading day immediately preceding the date on which the Company provides notice of redemption, during any 30 consecutive trading day period ending on, and including, the trading day immediately before the date the Company sends the related redemption notice. In addition, calling any Note for redemption will constitute a make-whole fundamental change with respect to that Note, in which case the conversion rate applicable to the conversion of that Note will be increased in certain circumstances if it is converted after it is called for redemption. Prior to March 15, 2025, the Notes will be convertible only under the following circumstances: • During any calendar quarter commencing after September 30, 2020, if, for at least 20 trading days (whether or not consecutive) during the 30 consecutive trading day period ending on, and including, the last trading day of the immediately preceding calendar quarter, the last reported sale price per share of the Company’s common stock on such trading day exceeds 130% of the applicable conversion price on such trading day; • During the five business day period after any five consecutive trading day period in which, for each day of that period, the trading price per $1,000 principal amount of Notes for such trading day was less than 98% of the product of the last reported sale price of the Company’s common stock and the applicable conversion rate on such trading day; • Upon the occurrence of specified corporate transactions; or • If the Company calls any notes for redemption. On and after March 15, 2025, until the close of business on the scheduled trading day immediately preceding the maturity date, holders may convert all or a portion of their Notes, in multiples of $1,000 principal amount, at any time, regardless of the foregoing circumstances. Upon conversion, the Notes will be settled, at the Company’s election, in cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock. It is the Company’s current intent to settle conversions of the Notes through combination settlement, which involves repayment of the principal portion in cash and any excess of the conversion value over the principal amount in shares of its common stock. The Notes are unsecured and unsubordinated obligations of the Company and will rank senior in right of payment to any of future indebtedness of the Company that is expressly subordinated in right of payment to the Notes; rank equal in right of payment to any existing and future unsecured indebtedness of the Company that is not so subordinated; be effectively subordinated in right of payment to any secured indebtedness of the Company to the extent of the value of the assets securing such indebtedness; and be structurally subordinated to all existing and future indebtedness and other liabilities and obligations incurred by future subsidiaries of the Company. If bankruptcy, insolvency, or reorganization occurs with respect to the Company (and not solely with respect to a significant subsidiary of the Company), then the principal amount of, and all accrued and unpaid interest on, all of the Notes then outstanding will immediately become due and payable without any further action or notice by any person. If an event of default (other than bankruptcy, insolvency, or reorganization with respect to the Company and not solely with respect to a significant subsidiary of ours) occurs and is continuing, then, with the exception of certain reporting events of default, the trustee, by notice to the Company, or noteholders of at least 25% of the aggregate principal amount of notes then outstanding, by notice to us and the trustee, may declare the principal amount of, and all accrued and unpaid interest on, all of the Notes then outstanding to become due and payable immediately. In accounting for the issuance of the Notes, the Company separately accounted for the liability and equity components of the Notes by allocating the proceeds between the liability component and the embedded conversion options, or equity component, due to Company’s ability to settle the Notes in cash, its common stock, or a combination of cash and common stock at Company’s option. The allocation was done by first estimating the fair value of the liability component and the residual value was assigned to the equity component. The value of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The allocation was performed in a manner that reflected the Company’s non-convertible debt borrowing rate for similar debt. The interest rate of 5.67% was used to compute the initial fair value of the liability component of $152.7 million. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. The net carrying amount of the liability component of the Notes was as follows: September 30, 2020 Principal $ 172,500 Unamortized debt discount (18,814 ) Unamortized debt issuance costs (5,629 ) Net carrying amount $ 148,057 The net carrying amount of the equity component of the Notes was as follows: September 30, 2020 Proceeds allocated to the conversion options (debt discount) $ 19,787 Issuance costs (767 ) Net carrying amount $ 19,020 In connection with the issuance of the Notes, the Company incurred approximately $6.7 million of debt issuance costs, which primarily consisted of initial purchasers’ discounts and legal and other professional fees. The Company allocated these costs to the liability and equity components based on the allocation of the proceeds. The portion of these costs allocated to the equity component totaling approximately $0.8 million was recorded as a reduction to additional paid-in capital. The portion of these costs allocated to the liability component totaling approximately $5.9 million was recorded as a reduction in the carrying value of the debt on the condensed balance sheet and is amortized to interest expense using the effective interest method over the expected life of the Notes or approximately its five-year term. The effective interest rate on the liability component of the Notes for the period from the date of issuance through September 30, 2020 was 6.4%. The following table sets forth the amounts recorded in interest expense related to the Notes from the date of issuance through September 30, 2020: Amount Contractual interest expense $ 1,496 Amortization of debt discount 974 Amortization of debt issuance costs 294 Total interest and amortization expense $ 2,764 Future minimum payments under the Notes as of September 30, 2020, are as follows: Fiscal Year Amount Remainder of 2020 $ 2,574 2021 5,175 2022 5,175 2023 5,175 2024 5,175 2025 175,088 Total future payments 198,362 Less amounts representing interest (25,862 ) Total principal amount $ 172,500 Capped Call Transactions with Respect to the Notes In June 2020, in connection with the issuance of the Notes, including the initial purchasers’ exercise of the option to purchase additional Notes, the Company entered into capped call transactions with respect to its common stock (the “Purchased Calls”) with certain financial institutions (collectively, the “Counterparties”). The Company paid an aggregate amount of approximately $22.5 million to the Counterparties for the Purchased Calls. The Purchased Calls cover, subject to anti-dilution adjustments that are intended to be substantially identical to those in the Notes, approximately 9,705,454 shares of the Company’s common stock at a strike price that corresponds to the initial conversion price of the Notes, also subject to adjustment, and are exercisable upon conversion of the Notes. The Purchased Call are subject to adjustment upon the occurrence of specified extraordinary events affecting the Company, including merger events, tender offer and announcement events. In addition, the Purchase Calls are subject to certain specified additional disruption events that may give rise to a termination of the Purchased Calls, including nationalization, insolvency or delisting, changes in law, failures to deliver, insolvency filings and hedging disruptions. The Purchased Calls settle in components commencing on April 16, 2025 with the last component scheduled to expire on June 12, 2025. The cap price of the capped call transactions is initially $27.88 per share, which represents a premium of 100.0% over the closing price of the Company’s common stock of $13.94 per share on June 10, 2020, and is subject to certain adjustments under the terms of the capped call transactions. The Company expects to receive from the Counterparties a number of shares of the Company’s common stock or, at the Company’s election (subject to certain conditions), cash, with an aggregate market value (or, in the case of cash settlement, in an amount) approximately equal to the product of such excess times the number of shares of the Company’s common stock relating to the Purchased Calls being exercised. These Capped Call instruments meet the conditions outlined in ASC 815-40 to be classified in stockholders’ equity, are not accounted for as derivatives, and are not subsequently remeasured as long as the conditions for equity classification continue to be met. The Company recorded a reduction to additional paid-in capital of approximately $22.5 million during the three months ended June 30, 2020 related to the premium payments for the Capped Call Transactions. Term Loans In 2013, the Company entered into an agreement to obtain a term loan facility (“Term Loan Facility”) in the amount of $5.0 million for general corporate purposes and working capital expenditures. In 2014, 2015 and 2016, the Company amended its Term Loan Facility to increase the amount borrowed under the facility by $11.6 million. The Term Loan Facility is secured by liens on substantially all of the Company’s present and future assets. The Term Loan Facility includes affirmative, negative and financial covenants that restrict the Company’s ability to, among other things, incur additional indebtedness, make investments, sell or otherwise dispose of assets, pay dividends or repurchase stock. The Term Loan Facility’s financial covenants required the Company to achieve at least 80% of its forecasted gross revenue and a liquidity ratio on a monthly basis. In 2017, the Company executed the eighth amendment (“Eight Amendment”) to the Term Loan Facility. The Eighth Amendment refinanced the $15.0 million repayment schedule to be two term loans, which included a $7.5 million interest only term loan with a maturity date of January 31, 2019 (“Term Loan I”), and the remaining $7.5 million under the existing Term Loan Facility with a maturity date of January 1, 2020 (“Term Loan II”) (together the “Term Loans”). In 2018, the Company entered into the ninth, tenth, eleventh, and twelfth amendment (“Ninth Amendment,” “Tenth Amendment,” “Eleventh Amendment” and “Twelfth Amendment”) to the existing Term Loans. The Ninth Amendment removed the liquidity ratio covenant, amended Term Loan I to be due in 30 equal monthly installments, plus all accrued interest, beginning July 31, 2018, increased the variable annual interest rate from 0.10% above the prime rate to 0.35% above the prime rate and extended the maturity date of Term Loan I to January 31, 2021. The Eighth Amendment and Ninth Amendment required the Company to pay a combined success fee of $0.3 million upon (1) any sale or licensing of all or substantially all of the Company’s assets, (2) any change in control of the Company, or (3) an initial public offering of the Company’s equity securities. The Ninth Amendment also required the Company to pay an additional success fee of $0.1 million upon the sale or issuance of the Company’s equity securities or subordinated debt securities for net cash proceeds of at least $50.0 million on or prior to June 30, 2018. The Company paid the $0.1 million success fee upon the Series G convertible preferred stock financing in June 2018 and the $0.3 million success fee related to its IPO in July 2019. The Tenth and Twelfth Amendments adjusted and waived certain covenant violations which were subsequently amended and met. The Eleventh Amendment provided an additional letter of credit of $1.5 million for corporate credit cards with a maturity date of August 1, 2019. On July 26, 2019 the Company fully repaid the principal of its Term Loans in the amount of $6.5 million. With the repayment of the term loans, the Company was no longer subject to debt covenants as of September 30, 2020. Interest expense related to the Term Loans was zero and immaterial for the three months ended September 30, 2020 and 2019, respectively. During the nine months ended September 30, 2020 and 2019, the Company recorded interest expense related to the Term Loans of zero and $0.6 million, respectively. Warrants Issued with Term Loan Facility During the period from 2013 to 2016, in connection with the Term Loan Facility, the Company issued convertible preferred stock warrants, which included warrants to purchase 131,652 shares of its Series B convertible preferred stock with an exercise price of $1.03 per share, 6,868 shares of its Series C convertible preferred stock with an exercise price of $2.18 per share, 43,010 shares of its Series D convertible preferred stock with an exercise price of $2.79 per share and 25,597 shares of its Series E convertible preferred stock with an exercise price of $2.93 per share (together the “Convertible Preferred Stock Warrants”). The Convertible Preferred Stock Warrants were exercisable from the date of issuance and have a 10-year term. The initial estimated fair value of the Convertible Preferred Stock Warrants was recorded as convertible preferred stock warrant liability with an offset to the debt discount associated with the Term Loan Facility. The debt discount is amortized to interest expense over the repayment period of the loan using the effective-interest method. All convertible Preferred Stock Warrants were converted to common stock warrants and exercised through net share settlement in July 2019. No warrants were outstanding as of September 30, 2020.

Convertible Preferred Stock and

Convertible Preferred Stock and Redeemable Convertible Preferred Stock	9 Months Ended
	Sep. 30, 2020
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock and Redeemable Convertible Preferred Stock	Note 7. Convertible Preferred Stock and Redeemable Convertible Preferred Stock In March 2019, the Company sold 6,350,345 shares of Series H redeemable convertible preferred stock and 3,831,766 shares of Series H convertible preferred stock at $6.8748 per share to new and existing investors for aggregate gross proceeds of $70.0 million. At March 31, 2019, convertible preferred stock and redeemable convertible preferred stock consisted of the following (in thousands, except share amounts): March 31, 2019 Shares Authorized Shares Issued and Outstanding Net Carrying Value Aggregate Liquidation Preference Series A 18,960,000 18,941,619 $ 9,161 $ 9,217 Series B 13,784,443 13,652,791 13,774 14,000 Series C 9,335,659 9,328,791 20,289 20,374 Series D 14,367,652 14,324,642 39,886 40,000 Series E 13,612,543 13,586,946 39,880 40,000 Series F 12,956,724 12,956,724 56,154 58,397 Series G 21,986,733 21,986,733 118,325 123,881 Series H 10,182,113 10,182,111 69,937 70,138 Total 115,185,867 114,960,357 $ 367,406 $ 376,007 On July 2, 2019 and

Share-based Compensation Plans

Share-based Compensation Plans	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-based Compensation Plans	Note 8. Share-based Compensation Plans 2011 Equity Incentive Plan In 2011, the Company adopted the Equity Incentive Plan (2011 Plan) authorizing the granting of incentive stock options (ISOs) and non-statutory stock options (NSOs) to eligible participants for up to 12,987,255 shares of common stock. Under the 2011 Plan, incentive stock options and non-statutory stock options are to be granted at an exercise price that is no less than 100% of the fair value of the stock at the date of grant. Options generally vest over four years and are exercisable for up to 10 years after the date of grant. Incentive stock options granted to stockholders who own more than 10% of the outstanding stock of the Company at the time of grant must be issued at an exercise price no less than 110% of the fair value of the stock on the date of grant. The 2011 Plan has been replaced by the Company’s 2019 Plan as defined below with respect to future equity awards. 2019 Equity Incentive Plan In connection with the Company’s initial public offering, the Company adopted the 2019 Equity Incentive Plan (the “2019 Plan”). The 2019 Plan allows the Company to grant stock options, stock appreciation rights, restricted stock, restricted stock units and performance awards to participants. Subject to the terms and conditions of the 2019 Plan, the initial number of shares authorized for grants under the 2019 Plan is 8,000,000. These available shares increase annually by an amount equal to the lesser of 8,000,000 shares, 5% of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31, or the number of shares determined by the Company’s board of directors. On August 4, 2020, the Company’s board of directors approved an increase of shares available for grant under the 2019 Plan by Employee Stock Purchase Plan In connection with the Company’s initial public offering, the Company adopted the Employee Stock Purchase Plan (ESPP). The Employee Stock Purchase Plan permits employees to purchase shares of common stock during six-month offering periods at a purchase price equal to the lesser of (1) 85% of the fair market value of a share of common stock on the first business day of such offering period and (2) 85% of the fair market value of a share of common stock on the last business day of such offering period. he Company selected the Black-Scholes option-pricing model as the method for determining the estimated fair value for the Company’s 2019 ESPP. Stock-based Compensation Total stock-based compensation expense, excluding compensation expense related to stock sales by current and former employees, by function was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Marketing $ 705 $ 145 $ 1,228 $ 287 Operations and technology 2,892 1,098 7,222 2,064 Selling, general and administrative 3,775 1,277 8,461 2,565 Total $ 7,372 $ 2,520 $ 16,911 $ 4,916 The amounts presented in the above table exclude compensation expense related to the stock sales by current and former employees. I

Leases

Leases	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Leases	Note 9. Leases The Company leases its corporate offices, retail spaces and merchandising and fulfillment facilities under various noncancelable operating leases with terms ranging from one year to fourteen years. The Company adopted ASU 2016-02 on January 1, 2020. At adoption, t he Company measured the lease liability at the present value of the future lease payments as of January 1, 2020, using the Company’s incremental borrowing rate for each lease. The Company derived the incremental borrowing rate by developing its own synthetic credit rating, corresponding yield curve, and the terms of each lease at the adoption date The corresponding right-of-use asset is valued at the amount of the lease liability adjusted for the remaining balance of unamortized lease incentives, prepaid rent and deferred rent as of the adoption date. The Company recorded operating lease costs of $6.2 million and $18.4 million for the three and nine months ended September 30, 2020, respectively. The Company also incurred $1.1 million and $3.1 million, respectively, of variable lease costs for the three and nine months ended September 30, 2020. The variable lease cost is comprised primarily of the Company’s proportionate share of operating expenses, property taxes and insurance. Rent expense under ASC 840 was $4.8 million and $13.4 million for the three and nine months ended September 30, 2019, respectively. Maturities of operating lease liabilities by fiscal year for the Company’s operating leases are as follows (in thousands): Fiscal Year Amount Remainder of 2020 $ 5,054 2021 24,205 2022 21,548 2023 20,168 2024 19,759 Thereafter 71,924 Total future minimum payments $ 162,658 Less: Imputed interest (35,715 ) Present value of operating lease liabilities $ 126,943 As of December 31, 2019, the Company’s future minimum lease payments under the noncancelable operating leases were as follows (in thousands): Year ending December 31, Amount 2020 $ 20,530 2021 22,059 2022 19,610 2023 18,307 2024 17,957 Thereafter 67,208 Total future minimum payments $ 165,671 Supplemental cash flow information related to the Company’s operating leases are as follows (in thousands): Nine Months Ended September 30, 2020 Operating cash flows used for operating leases $ 6,113 Operating lease assets obtained in exchange for operating lease liabilities $ 16,671 The weighted average remaining lease term and discount rate for the Company’s operating leases are as follows: September 30, 2020 Weighted average remaining lease term 7.3 years Weighted average discount rate 7.0 % The Company has leases for certain vehicles that are classified as finance leases. The finance lease right-of-use asset and finance lease liabilities for these vehicle leases are immaterial as of September 30, 2020.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 10. Commitments and Contingencies Noncancelable Purchase Commitments The Company has commitments for cloud services and other services in the ordinary course of business with varying expiration terms through 2022. As of September 30, 2020, there were no material changes to the Company’s noncancelable purchase commitments disclosed in the financial statements in the Annual Report on Form 10-K. Other Commitments In January 2018, the Company and the University of Arizona Foundation entered into an endowment agreement (the “Endowment Agreement”) to establish a fund (the “Fund”) to create and grow a gemology degree program in the Department of Geosciences at the University of Arizona (the “University”). The Company agreed to donate a total of $2.0 million, payable in four annual installments of $0.5 million starting in January 2018. There are no conditions that the University must meet to receive the funds nor any penalties to the University for nonperformance. The Endowment Agreement directs the use of the funds but contains no binding restrictions on the use of the funds. On the execution of the Endowment Agreement, the Company recognized $1.7 million expense for the estimated fair value of the grant, using a discount rate of 10%, to selling, general and administrative expenses in the statements of operations. The Company recognized a corresponding liability for the remaining installment payments and will recognize accretion of the liability as interest expense over the remaining term of the Endowment Agreement. Interest expense related to the accretion of the grant liability was not material in the three and nine months ended September 30, 2020 and 2019. As of September 30, 2020, the outstanding liability was $0.5 million, which Contingencies From time to time, the Company is subject to, and it is presently involved in, litigation and other legal proceedings and from time to time, the Company receives inquiries from government agencies. Accounting for contingencies requires the Company to use judgment related to both the likelihood of a loss and the estimate of the amount or range of loss. The Company records a loss contingency when it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. The Company discloses material contingencies when a loss is not probable but reasonably possible. On November 14, 2018, Chanel, Inc. (“Chanel”) filed a lawsuit against the Company in the U.S. District Court for the Southern District of New York bringing various trademark and advertising-related claims under the Lanham Act and New York state law analogues. Chanel alleges, among other things, that the Company has misrepresented certain counterfeit Chanel products as authentic Chanel products, that the Company’s resale of Chanel products confuses consumers into believing that Chanel is affiliated with the Company and involved in authenticating consignors ’ ’ On September 10, 2019, a purported shareholder class action complaint was filed against the Company, its officers and directors and the underwriters of its IPO in the Superior Court of the State of California in the County of San Mateo. Three additional purported class actions, also alleging claims arising from the IPO were subsequently filed in Marin County and San Francisco County Superior Courts. The San Mateo case was voluntarily dismissed, refiled in Marin County Superior Court and consolidated with the cases there. On January 10, 2020, the Marin County plaintiffs filed a consolidated amended complaint. The plaintiffs in the San Francisco Superior Court case have filed a request for dismissal. Separately an additional purported class action was filed in the United States District Court for the Northern District of California on November 25, 2019. On February 12, 2020, a lead plaintiff was appointed in the federal action and an Amended Consolidated Complaint was filed on March 31, 2020. Defendants’ filed a demurrer and motion to strike in the state court action on March 13, 2020 and filed a motion to stay the proceedings in favor of the federal action on May 1, 2020. On August 4, 2020, the court granted defendants’ motion to stay the state court action and deferred ruling on the demurrer and motion to strike pending the outcome of the federal court action. A motion to dismiss the federal court action was filed on May 15, 2020, which motion remains pending. The state and federal complaints each allege claims under the Securities Act of 1933 Indemnifications In the ordinary course of business, the Company may provide indemnifications of varying scope and terms to vendors, directors, officers and other parties with respect to certain matters including, but not limited to, losses arising out of the breach of such agreements, intellectual property infringement claims made by third parties and other liabilities relating to or arising from the Company's various services, or its acts or omissions. The Company has not incurred any material costs as a result of such indemnifications and have not accrued any liabilities related to such obligations in its financial statements.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Note 11. Income Taxes The quarterly income tax provision reflects an estimate of the corresponding quarter’s state taxes in the United States. The Company has reviewed all positive and negative evidence associated with the realizability of its deferred tax assets, and continues to maintain a full valuation allowance as of September 30, 2020. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security (CARES) Act (the “Act”) was signed into law. The Act provides various forms of income tax relief to companies including additional carryback opportunities for net operating losses (NOLs), and the potential offset of 100% of taxable income with NOLs (as opposed to only 80% before the Act’s enactment). The Act also temporarily increases the interest deductibility threshold from 30% to 50% of adjusted taxable income. Further, some companies can immediately expense qualified improvement property, instead of depreciating those costs over 39 years, for income tax purposes. Additionally, if improvement property is capitalized, the life to be used for amortization has been reduced from 39 years to 15 years. Given the Company’s tax attributes, specifically large net operating loss carryforwards, the Act and related provisions do not create immediate material tax relief. However, the Company continues to monitor the various tax provisions.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Net Loss Per Share	Note 12. Net Loss Per Share A reconciliation of the numerator and denominator used in the calculation of the basic and diluted net loss per share attributable to common stockholders is as follows (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Numerator Net loss attributable to common stockholders $ (43,305 ) $ (25,274 ) $ (124,489 ) $ (78,726 ) Denominator Weighted-average common shares outstanding used to calculate net loss per share attributable to common stockholders, basic and diluted 87,869,321 84,634,956 87,176,677 34,556,485 Net loss per share attributable to common stockholders, basic and diluted $ (0.49 ) $ (0.30 ) $ (1.43 ) $ (2.28 ) The following securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented, because including them would have been anti-dilutive (on an as-converted basis, except the Convertible Senior Notes): September 30, 2020 2019 Options to purchase common stock 6,444,997 9,417,490 Restricted stock units 4,625,248 551,549 Estimated shares issuable under the Employee Stock Purchase Plan 93,853 — Assumed conversion of the Convertible Senior Notes 9,705,454 — Total 20,869,552 9,969,039 The Notes issued in June 2020 are convertible, based on the applicable conversion rate, into cash, shares of the Company’s common stock or a combination thereof, at the Company’s election. The impact of the assumed conversion to diluted net income per share is computed using the treasury stock method.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	Note 13. Subsequent Events Leases In November 2020, the Company signed a new noncancelable operating lease for its fifth warehouse in Arizona. The lease term is through May 31, 2031 with an option to extend for up to ten years. The minimum lease payments for the initial lease term total $31.0 million.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of expenses during the reporting period. Significant items subject to such estimates and assumptions include those related to revenue recognition, including the returns reserve and material right related to the Company’s tiered consignor commission plan, valuation of inventory, software development costs, stock-based compensation, redemption value of redeemable convertible preferred stock, incremental borrowing rates related to lease liability, fair value of the liability component of convertible senior notes, and other contingencies. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates. The Company assessed the impacts of the pandemic on the estimates and assumptions used in preparing these financial statements. In particular, the Company is monitoring its returns reserve and adjusting in response to changing consumer behaviors. Its estimates may change as new events occur and additional information is obtained; any such changes will be recognized in the financial statements. Actual results could differ from estimates, and any such differences may be material to the financial statements.
Net Loss per Share Attributable to Common Stockholders	Net Loss per Share Attributable to Common Stockholders The Company follows the two-class method when computing net loss per common share when shares are issued that meet the definition of participating securities. The two-class method determines net loss per common share for each class of common stock and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income (loss) available or attributable to common stockholders for the period to be allocated between common stock and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. Before the IPO, the Company’s redeemable convertible preferred stock and convertible preferred stock were considered participating securities. However, the holders of such shares did not have a contractual obligation to participate in the Company’s losses. The Company’s convertible senior notes are participating securities as they give the holders the right to receive dividends if dividend or distribution declared to the common stockholders is equal to or greater than the last reported sale price of the Company’s common stock on the trading day immediately preceding the ex-dividend date for such dividend or distribution No . For periods in which the Company reports net losses, diluted net loss per common share attributable to common stockholders is the same as basic net loss per common share attributable to common stockholders, because potentially dilutive common shares and assumed conversion of the convertible senior notes are not assumed to have been issued within the calculation, if their effect is anti-dilutive.
Revenue Recognition	Revenue Recognition The Company generates revenue from the sale of pre-owned luxury goods through its online marketplace and retail locations. Consignment and Service Revenue The Company provides a service to sell pre-owned luxury goods on behalf of consignors to buyers through its online marketplace and retail locations. The Company retains a percentage of the proceeds received as payment for its consignment service, which the Company refers to as its take rate. The Company reports consignment revenue on a net basis as an agent and not the gross amount collected from the buyer. Title to the consigned goods remain with the consignor until transferred to the buyer subsequent to purchase of the consigned goods and expiration of the allotted return period. The Company does not take title of consigned goods at any time except in certain cases where returned goods become Company-owned inventory. The Company recognizes consignment revenue upon purchase of the consigned good by the buyer as its performance obligation of providing consignment services to the consignor is satisfied at that point. Consignment revenue is recognized net of certain buyer incentives and estimated returns and cancellations. The Company recognizes a returns reserve based on historical experience, which is recorded in other accrued and current liabilities on the condensed balance sheets (see Note 5). Sales tax assessed by governmental authorities is excluded from revenue. Certain transactions provide consignors with a material right resulting from the tiered consignor commission plan. Under this plan, the amount an individual consignor receives for future sales of consigned goods may be dependent on previous consignment sales for that consignor within his/her consignment period. Accordingly, in certain consignment transactions, a small portion of the Company’s consignment revenue is allocated to such material right using the portfolio method and recorded as deferred revenue, which is recorded in other accrued and current liabilities on the condensed balance sheets. The Company charges shipping fees to buyers and has elected to treat shipping and handling activities performed after control transfers to the buyer as fulfillment activities. All outbound shipping and handling costs are accounted for as fulfillment costs in cost of consignment and service revenue at the time revenue is recognized. The Company also generates subscription revenue from monthly memberships allowing buyers early access to shop for luxury goods. The buyers receive the early access and other benefits over the term of the subscription period, which represents a single stand-ready performance obligation. Therefore, the subscription fees paid by the buyer are recognized over the monthly subscription period. Subscription revenue was not material in the three months and nine months ended September 30, 2020 and 2019. Direct Revenue The Company generates direct revenue from the sale of Company-owned inventory. The Company recognizes direct revenue on a gross basis upon shipment of the purchased good to the buyer as the Company acts as the principal in the transaction. Direct revenue is recognized net of incentives and estimated returns. Sales tax assessed by governmental authorities is excluded from revenue. Cost of direct revenue is also recognized upon shipment to the buyer in an amount equal to that paid to the consignor from the original consignment sale, an amount equal to that paid as a direct purchase from a third party, or the lower of cost of the inventory purchased and its net realizable value. Incentives Promotional incentives, which include basket promotional code discounts and other credits, may periodically be offered to consignors and buyers. These are treated as a reduction of consignment and service revenue and direct revenue. Additionally, the Company may offer site credits to buyers on current transactions to be applied towards future transactions, which are accounted as deferred revenue and included in other accrued and current liabilities on the condensed balance sheets. Contract Liabilities The Company’s contractual liabilities consist of deferred revenue for material rights primarily related to the tiered consignor commission plan totaling $1.3 million as of September 30, 2020 and
Cost of Revenue	Cost of Revenue Cost of consignment and service revenue consist of shipping costs, credit card fees, packaging, customer service personnel-related costs, and website hosting services. Cost of direct revenue consists of the cost of goods sold, credit card fees, packaging, customer service personnel-related costs, and website hosting services.
Stock-based Compensation	Stock-based Compensation Stock-based compensation expense related to employees is measured based on the grant-date fair value of the awards. Compensation expense is recognized in the statements of operations over the period during which the employee is required to perform services in exchange for the award (the vesting period of the applicable award) using the straight-line method. The Company estimates the fair value of stock options granted using the Black-Scholes option pricing model and accounts for forfeitures as they occur. The fair value of restricted stock units (“RSUs”) is estimated based on the fair market value of the Company’s common stock on the date of grant, which is determined based on the closing price of the Company’s common stock. Prior to the IPO, certain employees have sold their shares of the Company’s common stock to the Company’s existing investors. In such secondary sale transactions, the Company recorded the difference in purchase price and the fair value of such shares as compensation expense within selling, general and administrative in the statements of operations and a corresponding credit to additional paid-in capital.
Cash, Cash Equivalents	Cash, Cash Equivalents The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents consist primarily of amounts invested in U.S. treasury securities.
Short-term Investments	Short-term Investments The Company has classified and accounted for its short-term investments as available-for-sale which are carried at fair value on its condensed balance sheets. Available-for-sale securities with remaining maturities of 12 months or less are classified as short term and available-for-sale securities with remaining maturities greater than 12 months are classified as long term. The Company evaluates its short-term investments periodically for possible impairment. A decline in the fair value below the amortized costs of the short-term investment is considered an other-than-temporary impairment if the Company has the intent to sell the short-term investments or it is more likely than not that the Company will be required to sell the short-term investment before recovery of the entire amortized cost basis.
Inventory, Net	Inventory, Net Inventory primarily consists of finished goods arising from goods returned after the title has transferred from the buyer to the Company in an amount equal to that paid to the consignor. The Company also periodically purchases finished goods directly from vendors. Inventory is valued at the lower of cost and net realizable value using the specific identification method and the Company records provisions, as appropriate, to write down obsolete and excess inventory to estimated net realizable value. After the inventory value is reduced, adjustments are not made to increase it from the estimated net realizable value. Our provisions to write down obsolete and excess inventory to net realizable value have not been material as of September 30, 2020 and December 31, 2019.
Software Development Costs	Software Development Costs Proprietary software includes the costs of developing the Company’s internal proprietary business platform and automation projects. The Company capitalizes qualifying proprietary software development costs that are incurred during the application development stage. Capitalization of costs begins when two criteria are met: (1) the preliminary project stage is completed and (2) it is probable that the software will be completed and used for its intended function. Such costs are capitalized in the period incurred. Capitalization ceases and amortization begins when the software is substantially complete and ready for its intended use, including the completion of all significant testing. Costs related to preliminary project activities and post-implementation operating activities are expensed as incurred.
Accretion of Redeemable Convertible Preferred Stock	Accretion of Redeemable Convertible Preferred Stock The carrying value of the redeemable convertible preferred stock that is probable of redemption is accreted to redemption value from the date of issuance to the earliest redemption date using the effective interest method until redemption is no longer probable. Increases to the carrying value of redeemable convertible preferred stock recognized in each period are charged to additional paid-in capital, or in the absence of additional paid-in capital, charged to accumulated deficit.
Convertible Preferred Stock Warrant Liability	Convertible Preferred Stock Warrant Liability The Company issued convertible preferred stock warrants in conjunction with the issuance of debt. Such warrants were recorded as other noncurrent liabilities on the condensed balance sheets at their estimated fair value because the shares underlying the warrants may obligate the Company to transfer assets to the holders at a future date under certain circumstances such as a deemed liquidation event. The warrants are subject to re-measurement at each balance sheet date and the change in fair value, if any, is included in other income (expense), net. The Company continued to remeasure these warrants until the earlier of the expiration, exercise or conversion of the convertible preferred stock warrants into common warrants, which occurred upon the completion of the IPO on July 2, 2019. In connection with the completion of the IPO, the convertible preferred stock warrants automatically converted into common stock warrants. Upon conversion of the convertible preferred stock warrants, the related convertible preferred stock warrant liability was reclassified to additional paid-in capital.
Leases	Leases Prior to the adoption of ASC 842 on January 1, 2020 Leases are reviewed for classification as operating or capital leases. For operating leases, the Company recognizes rent on a straight-line basis over the term of the lease. The Company records the difference between cash payments and rent expense recognized as a deferred rent liability included in other accrued and current liabilities and other noncurrent liabilities on the condensed balance sheets. Incentives granted under the Company’s facility leases, including allowances to fund leasehold improvements, are deferred and are recognized as adjustments to rental expense on a straight-line basis over the term of the lease. Subsequent to the adoption of ASC 842 on January 1, 2020 Contracts that have been determined to convey the right to use an identified asset are evaluated for classification as an operating or finance lease. For the Company’s operating leases, the Company records a lease liability based on the present value of the lease payments at lease inception, using the applicable incremental borrowing rate. The Company estimates the incremental borrowing rate by developing its own synthetic credit rating, corresponding yield curve, and the terms of each lease at the lease commencement date The Company has elected the practical expedients that allows for the combination of lease components and non-lease components and to record short-term leases as lease expense on a straight-line basis on the condensed statements of operations. Variable lease payments are recorded as expense as they are incurred. The Company has finance leases for several vehicles, and the amounts of finance lease right-of-use assets and finance lease liabilities have been immaterial to date.
Convertible Senior Notes	Convertible Senior Notes In accordance with ASC 470, convertible debt instruments that may be settled in cash or other assets, or partially in cash, upon conversion, are separately accounted for as long-term debt and equity components (or conversion feature). The accounting applies to the Company’s convertible senior notes (the “Notes”)
Capped Call Transactions	Capped Call Transactions In June 2020, in connection with the issuance of its convertible senior notes, the Company entered into Capped Call Transactions (see Note 6). The Capped Call Transactions are expected generally to reduce the potential dilution to the holders of the Company’s common stock upon any conversion of the Notes and/or offset any cash payments the Company is required to make in excess of the principal amount of converted Notes, with such reduction and/or offset subject to a cap based on the cap price. The capped calls meet the conditions outlined in ASC 815-40, Derivatives and Hedging
Debt Issuance Costs	Debt Issuance Costs Debt issuance costs are amortized to interest expense over the estimated life of the related debt based on the effective interest method. In accordance with ASC 835, Interest
Concentrations of Credit Risks	Concentrations of Credit Risks Financial instruments that potentially subject the Company to concentrations of credit risk consist of cash and cash equivalents, accounts receivable, and investments. At times, such amount may exceed federally-insured limits. The Company reduces credit risk by placing its cash, cash equivalents, and investments with major financial institutions within the United States. As of September 30, 2020 and December 31, 2019, there were no customers that represented 10% or more of the Company’s accounts receivable balance and there were no customers that individually exceeded 10% of the Company’s total revenue for each of the three and nine months ended September 30, 2020 and 2019.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) The Company is an emerging growth company “EGC”, as defined in the Jumpstart Our Business Startups Act of 2012 (JOBS Act). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The new standard is effective for the Company beginning January 1, 2022. The Company chose to early adopt the standard on January 1, 2020. The Company can choose to adopt new or revised accounting standards earlier than such time those standards apply to private companies and retain its election for the extended transition period, if early adoption is permitted for all entities. The Company adopted and began applying the standard on January 1, 2020 using the modified retrospective approach and applied it to all existing leases as of the adoption date, which allows for a cumulative-effect adjustment to retained earnings on the adoption date. The Company will continue to present prior period amounts under ASC 840. In addition, the Company elected the package of practical expedients permitted under the transition guidance within the new standard which does not require the Company to reassess whether contracts that expired prior to the adoption date contained an embedded lease, reassess historical lease classification, or evaluate direct costs for leases that were in effect at the adoption date. As a result of implementing this guidance, the Company recognized $110.3 million in right of use assets as of January 1, 2020. The Company also recorded $12.8 million in current operating lease liabilities and $106.2 million in operating lease liabilities, net of current portion in its condensed balance sheet as of January 1, 2020. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820)
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements As an EGC, the Company has elected to retain the ability to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that the Company (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opt out of the extended transition period provided in the JOBS Act. As a result, the Company’s financial statements may not be comparable to companies that comply with new or revised accounting pronouncements as of public company effective dates. Because the market value of the Company’s common stock held by non-affiliates exceeded $700 million as of June 30, 2020, the Company will be deemed a “large accelerated filer” under the Exchange Act and will lose emerging growth company status as of December 31, 2020. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments (Topic 326) As an EGC, the Company has not yet adopted the standard. However, the Company will be required to adopt the standard as of January 1, 2020 in its 2020 10-K. The Company does not expect the adoption of this standard to have a material impact on the operating results. In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718), In August 2020, the FASB issued ASU 2020-06, Debt – Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity which simplifies accounting for convertible instruments by removing major separation models required under current U.S. GAAP. ASU 2020-06 removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and it also simplifies the diluted earnings per share calculation in certain areas.

Cash, Cash Equivalents and Sh_2

Cash, Cash Equivalents and Short-term Investments (Tables)	9 Months Ended
	Sep. 30, 2020
Cash And Cash Equivalents [Abstract]
Summary of Estimated Value of Cash, Cash Equivalents and Short-term Investments	The following tables summarize the estimated value of the Company’s cash, cash equivalents and short-term investments (in thousands): September 30, 2020 Amortized Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 191,279 $ — $ — $ 191,279 Money market fund 151,813 — — 151,813 Total cash and cash equivalents $ 343,092 $ — $ — $ 343,092 Short-term investments: U.S. Treasury securities $ 16,015 $ 40 $ — $ 16,055 Corporate bonds 36,034 67 — 36,101 Total short-term investments $ 52,049 $ 107 $ — $ 52,156 December 31, 2019 Amortized Cost Unrealized Gain Unrealized Loss Fair Value Cash and cash equivalents: Cash $ 111,319 $ — $ — $ 111,319 U.S. Treasury securities 29,981 — — 29,981 Money market fund 5,399 — — 5,399 Corporate bonds 3,749 — — 3,749 Agency bonds 2,000 — — 2,000 Commercial paper 1,998 — — 1,998 Total cash and cash equivalents $ 154,446 $ — $ — $ 154,446 Short-term investments: U.S. Treasury securities $ 151,857 $ 13 $ — $ 151,870 Corporate bonds 38,149 — (5 ) 38,144 Agency bonds 11,028 — (2 ) 11,026 Commercial paper 7,770 1 — 7,771 Total short-term investments $ 208,804 $ 14 $ (7 ) $ 208,811

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Schedule of Financial Instruments Measured at Fair Value	The following tables provide the financial instruments measured at fair value (in thousands): September 30, 2020 Level 1 Level 2 Level 3 Total Assets Cash equivalents: Money market fund $ 151,813 $ — $ — $ 151,813 Total cash equivalents $ 151,813 $ — $ — $ 151,813 Short-term investments: U.S. Treasury securities $ 16,055 $ — $ — $ 16,055 Corporate bonds — 36,101 — 36,101 Total short-term investments $ 16,055 $ 36,101 $ — $ 52,156 December 31, 2019 Level 1 Level 2 Level 3 Total Assets Cash equivalents: U.S. Treasury securities $ 29,981 $ — $ — $ 29,981 Money market fund 5,399 — — 5,399 Corporate bonds — 3,749 — 3,749 Agency bonds — 2,000 — 2,000 Commercial paper — 1,998 — 1,998 Total cash equivalents $ 35,380 $ 7,747 $ — $ 43,127 Short-term investments: U.S. Treasury securities $ 151,870 $ — $ — $ 151,870 Corporate bonds — 38,144 — 38,144 Agency bonds — 11,026 — 11,026 Commercial paper — 7,771 — 7,771 Total short-term investments $ 151,870 $ 56,941 $ — $ 208,811

Condensed Balance Sheet Compo_2

Condensed Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2020
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consists of the following (in thousands): September 30, 2020 December 31, 2019 Proprietary software $ 23,288 $ 23,318 Furniture and equipment 25,742 21,083 Automobiles 667 718 Leasehold improvements 50,852 43,505 100,549 88,624 Less: accumulated depreciation and amortization (38,605 ) (32,793 ) Property and equipment, net $ 61,944 $ 55,831
Schedule of Other Accrued and Current Liabilities	Other accrued and current liabilities consist of the following (in thousands): September 30, 2020 December 31, 2019 Returns reserve $ 12,793 $ 17,005 Accrued compensation 14,043 11,626 Site credit liability 5,439 5,080 Accrued sales tax and other taxes 5,446 6,132 Deferred revenue 1,960 4,767 Accrued marketing and outside services 10,297 6,830 Accrued interest 1,496 — Other 4,293 3,127 Other accrued and current liabilities $ 55,767 $ 54,567

Debt and Convertible Preferre_2

Debt and Convertible Preferred Stock Warrants (Tables)	9 Months Ended
	Sep. 30, 2020
Amounts Recorded in Interest Expense Related to Notes	The following table sets forth the amounts recorded in interest expense related to the Notes from the date of issuance through September 30, 2020: Amount Contractual interest expense $ 1,496 Amortization of debt discount 974 Amortization of debt issuance costs 294 Total interest and amortization expense $ 2,764
Schedule of Future Minimum Payments Under Notes	Future minimum payments under the Notes as of September 30, 2020, are as follows: Fiscal Year Amount Remainder of 2020 $ 2,574 2021 5,175 2022 5,175 2023 5,175 2024 5,175 2025 175,088 Total future payments 198,362 Less amounts representing interest (25,862 ) Total principal amount $ 172,500
Notes as Liability Component
Schedule of Net Carrying Amount of Notes	The net carrying amount of the liability component of the Notes was as follows: September 30, 2020 Principal $ 172,500 Unamortized debt discount (18,814 ) Unamortized debt issuance costs (5,629 ) Net carrying amount $ 148,057
Notes as Equity Component
Schedule of Net Carrying Amount of Notes	The net carrying amount of the equity component of the Notes was as follows: September 30, 2020 Proceeds allocated to the conversion options (debt discount) $ 19,787 Issuance costs (767 ) Net carrying amount $ 19,020

Convertible Preferred Stock a_2

Convertible Preferred Stock and Redeemable Convertible Preferred Stock (Tables)	9 Months Ended
	Sep. 30, 2020
Temporary Equity Disclosure [Abstract]
Summary of Convertible Preferred Stock and Redeemable Convertible Preferred Stock	At March 31, 2019, convertible preferred stock and redeemable convertible preferred stock consisted of the following (in thousands, except share amounts): March 31, 2019 Shares Authorized Shares Issued and Outstanding Net Carrying Value Aggregate Liquidation Preference Series A 18,960,000 18,941,619 $ 9,161 $ 9,217 Series B 13,784,443 13,652,791 13,774 14,000 Series C 9,335,659 9,328,791 20,289 20,374 Series D 14,367,652 14,324,642 39,886 40,000 Series E 13,612,543 13,586,946 39,880 40,000 Series F 12,956,724 12,956,724 56,154 58,397 Series G 21,986,733 21,986,733 118,325 123,881 Series H 10,182,113 10,182,111 69,937 70,138 Total 115,185,867 114,960,357 $ 367,406 $ 376,007

Share-based Compensation Plans

Share-based Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Total Stock-based Compensation Expense, Excluding Compensation Expense Related to Stock Sales, by Function	Total stock-based compensation expense, excluding compensation expense related to stock sales by current and former employees, by function was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Marketing $ 705 $ 145 $ 1,228 $ 287 Operations and technology 2,892 1,098 7,222 2,064 Selling, general and administrative 3,775 1,277 8,461 2,565 Total $ 7,372 $ 2,520 $ 16,911 $ 4,916

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Schedule of Maturities of Operating Lease Liabilities	Maturities of operating lease liabilities by fiscal year for the Company’s operating leases are as follows (in thousands): Fiscal Year Amount Remainder of 2020 $ 5,054 2021 24,205 2022 21,548 2023 20,168 2024 19,759 Thereafter 71,924 Total future minimum payments $ 162,658 Less: Imputed interest (35,715 ) Present value of operating lease liabilities $ 126,943
Schedule of Future Minimum Lease Payments Under Noncancelable Operating Leases	As of December 31, 2019, the Company’s future minimum lease payments under the noncancelable operating leases were as follows (in thousands): Year ending December 31, Amount 2020 $ 20,530 2021 22,059 2022 19,610 2023 18,307 2024 17,957 Thereafter 67,208 Total future minimum payments $ 165,671
Schedule of Supplemental Cash Flow Information Related to Operating Leases	Supplemental cash flow information related to the Company’s operating leases are as follows (in thousands): Nine Months Ended September 30, 2020 Operating cash flows used for operating leases $ 6,113 Operating lease assets obtained in exchange for operating lease liabilities $ 16,671
Schedule of Weighted Average Remaining Lease Term and Discount Rate for Operating Leases	The weighted average remaining lease term and discount rate for the Company’s operating leases are as follows: September 30, 2020 Weighted average remaining lease term 7.3 years Weighted average discount rate 7.0 %

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Schedule of Reconciliation of Numerator and Denominator Used in Calculation of Basic and Diluted Net Loss Per Share	A reconciliation of the numerator and denominator used in the calculation of the basic and diluted net loss per share attributable to common stockholders is as follows (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Numerator Net loss attributable to common stockholders $ (43,305 ) $ (25,274 ) $ (124,489 ) $ (78,726 ) Denominator Weighted-average common shares outstanding used to calculate net loss per share attributable to common stockholders, basic and diluted 87,869,321 84,634,956 87,176,677 34,556,485 Net loss per share attributable to common stockholders, basic and diluted $ (0.49 ) $ (0.30 ) $ (1.43 ) $ (2.28 )
Schedule of Anti-dilutive Securities Excluded from Computation of Diluted Net Loss Per Share	The following securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented, because including them would have been anti-dilutive (on an as-converted basis, except the Convertible Senior Notes): September 30, 2020 2019 Options to purchase common stock 6,444,997 9,417,490 Restricted stock units 4,625,248 551,549 Estimated shares issuable under the Employee Stock Purchase Plan 93,853 — Assumed conversion of the Convertible Senior Notes 9,705,454 — Total 20,869,552 9,969,039

Description of Business and B_2

Description of Business and Basis of Presentation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Jul. 02, 2019	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019	Mar. 31, 2019
Class Of Stock [Line Items]
Decrease in net revenues due to COVID-19		4.00%	5.00%
Common stock, shares authorized		500,000,000	500,000,000	500,000,000
Redeemable convertible preferred stock outstanding					114,960,357
Initial Public Offering
Class Of Stock [Line Items]
Number of common stock issued	15,000,000
Common stock issued price per share	$ 20
Net proceeds from issuance of initial public offering	$ 315.5
Underwriting discounts and commissions	24.1
Issuance costs	$ 5.3
Common stock, shares authorized	500,000,000
Undesignated preferred stock, shares authorized for issuance	50,000,000
Redeemable convertible preferred stock outstanding	114,960,357
Convertible preferred stock converted into common stock	58,363,606
Description of reverse stock split			On June 13, 2019 the Company effected a reverse split of shares of the Company’s common stock on a 1-for-2 basis
Reverse stock split ratio			0.5
Initial Public Offering | Common Stock Warrants
Class Of Stock [Line Items]
Conversion of preferred stock warrants into common stock warrants	103,563
Underwriters' Option to Purchase Additional Shares
Class Of Stock [Line Items]
Number of common stock issued	2,250,000
Common stock issued price per share	$ 20

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020USD ($)Customer	Sep. 30, 2019Customer	Sep. 30, 2020USD ($)Customer	Sep. 30, 2019Customer	Dec. 31, 2019USD ($)Customer	Jun. 30, 2020USD ($)	Jan. 01, 2020USD ($)
Summary Of Significant Accounting Policies [Line Items]
Contractual liabilities	$ 1,960,000		$ 1,960,000		$ 4,767,000
Unrealized gains and losses within accumulated other comprehensive income (loss), excepts other than temporary losses			0		$ 0
Right-of-use asset	115,013,000		115,013,000				$ 110,300,000
Current operating lease liabilities	15,263,000		15,263,000				12,800,000
Operating lease liabilities, net of current portion	$ 111,680,000		$ 111,680,000				$ 106,200,000
Market value of common stock held by non-affiliates						$ 700,000,000
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, early adoption	true		true
Date accounting standards update was adopted	Jan. 1, 2020		Jan. 1, 2020
Change in accounting principle, accounting standards update, transition option elected [Extensible List]			us-gaap:AccountingStandardsUpdate201602RetrospectiveMember
ASU 2018-13
Summary Of Significant Accounting Policies [Line Items]
Date accounting standards update was adopted	Jan. 1, 2020		Jan. 1, 2020
Change in accounting principle, accounting standards update, adopted	true		true
Change in accounting principle, accounting standards update, immaterial effect	true		true
Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Number of major customers | Customer			0		0
Total Revenue
Summary Of Significant Accounting Policies [Line Items]
Number of major customers | Customer	0	0	0	0
Deferred Revenue
Summary Of Significant Accounting Policies [Line Items]
Contractual liabilities	$ 1,300,000		$ 1,300,000		$ 3,500,000
Common Stock
Summary Of Significant Accounting Policies [Line Items]
Dividend or distribution declared	$ 0		$ 0

Cash, Cash Equivalents and Sh_3

Cash, Cash Equivalents and Short-term Investments - Summary of Estimated Value of Cash, Cash Equivalents and Short-term Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost	$ 343,092	$ 154,446
Cash and cash equivalents, fair value	343,092	154,446
Short-term investments, amortized cost	52,049	208,804
Short-term investments, unrealized gain	107	14
Short-term investments, unrealized loss		(7)
Short-term investments, fair value	52,156	208,811
U.S. Treasury Securities
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost		29,981
Cash and cash equivalents, fair value		29,981
Short-term investments, amortized cost	16,015	151,857
Short-term investments, unrealized gain	40	13
Short-term investments, fair value	16,055	151,870
Cash
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost	191,279	111,319
Cash and cash equivalents, fair value	191,279	111,319
Money Market Fund
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost	151,813	5,399
Cash and cash equivalents, fair value	151,813	5,399
Corporate Bonds
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost		3,749
Cash and cash equivalents, fair value		3,749
Short-term investments, amortized cost	36,034	38,149
Short-term investments, unrealized gain	67
Short-term investments, unrealized loss		(5)
Short-term investments, fair value	$ 36,101	38,144
Agency Bonds
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost		2,000
Cash and cash equivalents, fair value		2,000
Short-term investments, amortized cost		11,028
Short-term investments, unrealized loss		(2)
Short-term investments, fair value		11,026
Commercial Paper
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents, amortized cost		1,998
Cash and cash equivalents, fair value		1,998
Short-term investments, amortized cost		7,770
Short-term investments, unrealized gain		1
Short-term investments, fair value		$ 7,771

Cash, Cash Equivalents and Sh_4

Cash, Cash Equivalents and Short-term Investments - Additional Information (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Maximum
Cash And Cash Equivalents [Line Items]
Short term investments contractual maturity term	1 year	1 year

Fair Value Measurement - Additi

Fair Value Measurement - Additional Information (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Jun. 30, 2020	Jun. 15, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Asset transfers Level 1 to Level 2	$ 0	$ 0
Asset transfers Level 2 to Level 1	0	0
Asset transfers into Level 3	0	0
Asset transfers out of Level 3	0	0
Liabilities transfers Level 1 to Level 2	0	0
Liabilities transfers Level 2 to Level 1	0	0
Liability transfers into Level 3	0	0
Liability transfers out of Level 3	0	$ 0
Aggregate face amount	172,500,000
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated fair value based on market price	172,000,000
Convertible Senior Notes | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Aggregate face amount	$ 172,500,000
3.00% Convertible Senior Notes Due 2025
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Notes interest rate	3.00%		3.00%	3.00%
Fair value of liability	$ 152,700,000			$ 152,700,000
Discount on initial issuance				$ 19,800,000
Aggregate face amount			$ 172,500,000

Fair Value Measurement - Schedu

Fair Value Measurement - Schedule of Financial Instruments Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets
Cash equivalents	$ 343,092	$ 154,446
Short-term investments	52,156	208,811
Recurring
Assets
Cash equivalents		43,127
Short-term investments	52,156	208,811
Recurring | U.S. Treasury Securities
Assets
Cash equivalents		29,981
Short-term investments	16,055	151,870
Recurring | Money Market Fund
Assets
Cash equivalents	151,813	5,399
Recurring | Corporate Bonds
Assets
Cash equivalents		3,749
Short-term investments	36,101	38,144
Recurring | Agency Bonds
Assets
Cash equivalents		2,000
Short-term investments		11,026
Recurring | Commercial Paper
Assets
Cash equivalents	151,813	1,998
Short-term investments		7,771
Recurring | Level 1
Assets
Cash equivalents		35,380
Short-term investments	16,055	151,870
Recurring | Level 1 | U.S. Treasury Securities
Assets
Cash equivalents		29,981
Short-term investments	16,055	151,870
Recurring | Level 1 | Money Market Fund
Assets
Cash equivalents	151,813	5,399
Recurring | Level 1 | Commercial Paper
Assets
Cash equivalents	151,813
Recurring | Level 2
Assets
Cash equivalents		7,747
Short-term investments	36,101	56,941
Recurring | Level 2 | Corporate Bonds
Assets
Cash equivalents		3,749
Short-term investments	$ 36,101	38,144
Recurring | Level 2 | Agency Bonds
Assets
Cash equivalents		2,000
Short-term investments		11,026
Recurring | Level 2 | Commercial Paper
Assets
Cash equivalents		1,998
Short-term investments		$ 7,771

Condensed Balance Sheet Compo_3

Condensed Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 100,549	$ 88,624
Less: accumulated depreciation and amortization	(38,605)	(32,793)
Property and equipment, net	61,944	55,831
Proprietary Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	23,288	23,318
Furniture And Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	25,742	21,083
Automobiles
Property Plant And Equipment [Line Items]
Property and equipment, gross	667	718
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 50,852	$ 43,505

Condensed Balance Sheet Compo_4

Condensed Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Property Plant And Equipment [Line Items]
Depreciation and amortization expense on property and equipment	$ 4.9	$ 3.5	$ 13.7	$ 9.5
Proprietary Software
Property Plant And Equipment [Line Items]
Proprietary software taken out of service and fully depreciated	$ 6.8

Condensed Balance Sheet Compo_5

Condensed Balance Sheet Components - Schedule of Other Accrued and Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Returns reserve	$ 12,793	$ 17,005
Accrued compensation	14,043	11,626
Site credit liability	5,439	5,080
Accrued sales tax and other taxes	5,446	6,132
Deferred revenue	1,960	4,767
Accrued marketing and outside services	10,297	6,830
Accrued interest	1,496
Other	4,293	3,127
Other accrued and current liabilities	$ 55,767	$ 54,567

Debt and Convertible Preferre_3

Debt and Convertible Preferred Stock Warrants - Additional Information (Details)	Jun. 10, 2020$ / shares	Jul. 26, 2019USD ($)	Jun. 30, 2020USD ($)$ / sharesshares	Jul. 31, 2019USD ($)	Jun. 30, 2018USD ($)	Sep. 30, 2020USD ($)$ / sharesshares	Jun. 30, 2020USD ($)$ / sharesshares	Sep. 30, 2020USD ($)$ / sharesshares	Jun. 30, 2018USD ($)	Sep. 30, 2020USD ($)d$ / sharesshares	Sep. 30, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Jun. 15, 2020USD ($)	Dec. 31, 2013USD ($)
Debt Disclosure [Line Items]
Aggregate principal amount						$ 172,500,000		$ 172,500,000		$ 172,500,000
Proceeds from issuance of convertible senior notes, net of issuance costs										166,278,000
Purchase of capped call transactions							$ 22,546,000			22,546,000
Debt issuance costs						6,700,000		6,700,000		6,700,000
Equity component of convertible senior notes, net of issuance costs							$ 19,020,000			800,000
Liability component recorded as a reduction in carrying value of debt						5,900,000		$ 5,900,000		$ 5,900,000
Amortization period										5 years
Effective Interest rate								6.40%
Payment to counterparties for purchased calls			$ 22,500,000
Common stock subject to adjustment and exercisable upon conversion of initial notes | shares			9,705,454				9,705,454
Cap price of capped transactions | $ / shares	27.88
Derivative cap price as percentage on common stock price per share	100.00%
Closing price of common stock per share | $ / shares	$ 13.94
Reduction to additional paid premium payments for capped call transactions							$ 22,500,000
Long-term debt, gross						198,362,000		$ 198,362,000		$ 198,362,000
Interest expense related to term loans						$ 0		$ 2,764,000		$ 0	$ 600,000
Warrants outstanding | shares						0		0		0
Letter of Credit
Debt Disclosure [Line Items]
Debt instrument, maturity date												Aug. 1, 2019
Line of credit												$ 1,500,000
IPO
Debt Disclosure [Line Items]
Debt, success fee				$ 300,000
Series G Convertible Preferred Stock
Debt Disclosure [Line Items]
Debt, success fee					$ 100,000
Series B Convertible Preferred Stock
Debt Disclosure [Line Items]
Outstanding preferred stock warrants exercised (in shares) | shares						131,652		131,652		131,652
Exercise price of warrants (in dollars per share) | $ / shares						$ 1.03		$ 1.03		$ 1.03
Series C Convertible Preferred Stock
Debt Disclosure [Line Items]
Outstanding preferred stock warrants exercised (in shares) | shares						6,868		6,868		6,868
Exercise price of warrants (in dollars per share) | $ / shares						$ 2.18		$ 2.18		$ 2.18
Series D Convertible Preferred Stock
Debt Disclosure [Line Items]
Outstanding preferred stock warrants exercised (in shares) | shares						43,010		43,010		43,010
Exercise price of warrants (in dollars per share) | $ / shares						$ 2.79		$ 2.79		$ 2.79
Series E Convertible Preferred Stock
Debt Disclosure [Line Items]
Outstanding preferred stock warrants exercised (in shares) | shares						25,597		25,597		25,597
Exercise price of warrants (in dollars per share) | $ / shares						$ 2.93		$ 2.93		$ 2.93
Convertible Preferred Stock
Debt Disclosure [Line Items]
Warrant term										10 years
Term Loan Facility
Debt Disclosure [Line Items]
Maximum borrowing capacity															$ 5,000,000
Increase in borrowing capacity										$ 11,600,000
Debt instrument required covenants percentage on forecasted gross revenue										80.00%
Debt, combined success fee												$ 300,000
Debt, additional success fee									$ 100,000
Net cash proceeds from subordinated debt securities									$ 50,000,000
Term Loans
Debt Disclosure [Line Items]
Long-term debt, gross													$ 15,000,000
Repayments on loans		$ 6,500,000
Term Loan I
Debt Disclosure [Line Items]
Debt instrument, maturity date												Jan. 31, 2021	Jan. 31, 2019
Notes frequency of periodic payment										30 equal monthly installments
Effective Interest rate												0.35%	0.10%
Long-term debt, gross													$ 7,500,000
Term Loan II
Debt Disclosure [Line Items]
Debt instrument, maturity date													Jan. 1, 2020
Long-term debt, gross													$ 7,500,000
Notes
Debt Disclosure [Line Items]
Aggregate principal amount			$ 172,500,000				$ 172,500,000
Notes interest rate			3.00%			3.00%	3.00%	3.00%		3.00%				3.00%
Debt instrument, maturity date										Jun. 15, 2025
Proceeds from issuance of convertible senior notes, net of issuance costs			$ 165,800,000
Purchase of capped call transactions			$ 22,500,000
Notes frequency of periodic payment										semi-annually
Number of shares per $1,000 principal amount | shares			56.2635
Initial conversion price | $ / shares			$ 17.77				$ 17.77
Notes, threshold percentage of stock price trigger										130.00%
Notes, threshold trading days | d										20
Notes, threshold consecutive trading days | d										30
Percentage on aggregate principal amount of notes to be payable upon the event of default										25.00%
Interest rate used to compute initial fair value of liability										5.67%
Fair value of liability						$ 152,700,000		$ 152,700,000		$ 152,700,000				$ 152,700,000
Notes | Purchased Calls
Debt Disclosure [Line Items]
Expiration date										Jun. 12, 2025
Notes | Conversion Option One
Debt Disclosure [Line Items]
Notes, threshold percentage of stock price trigger										130.00%
Notes, threshold trading days | d										20
Notes, threshold consecutive trading days | d										30
Notes | Conversion Option Two
Debt Disclosure [Line Items]
Notes, threshold percentage of stock price trigger										98.00%
Notes, threshold consecutive trading days | d										5
Notes, threshold trading days | d										5
Notes | Initial Purchasers
Debt Disclosure [Line Items]
Aggregate principal amount			$ 22,500,000				$ 22,500,000

Debt and Convertible Preferre_4

Debt and Convertible Preferred Stock Warrants - Schedule of Net Carrying Amount of Liability Component of Notes (Details)	Sep. 30, 2020USD ($)
Debt Disclosure [Line Items]
Principal	$ 172,500,000
Unamortized debt issuance costs	(5,900,000)
Notes as Liability Component
Debt Disclosure [Line Items]
Principal	172,500,000
Unamortized debt discount	(18,814,000)
Unamortized debt issuance costs	(5,629,000)
Net carrying amount	$ 148,057,000

Debt and Convertible Preferre_5

Debt and Convertible Preferred Stock Warrants - Schedule of Net Carrying Amount of Equity Component of Notes (Details) $ in Thousands	Sep. 30, 2020USD ($)
Debt Disclosure [Line Items]
Issuance costs	$ (6,700)
Notes as Equity Component
Debt Disclosure [Line Items]
Proceeds allocated to the conversion options (debt discount)	19,787
Issuance costs	(767)
Net carrying amount	$ 19,020

Debt and Convertible Preferre_6

Debt and Convertible Preferred Stock Warrants - Amounts Recorded in Interest Expense Related to Notes (Details) - USD ($)	3 Months Ended	4 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Debt Disclosure [Abstract]
Contractual interest expense		$ 1,496,000
Amortization of debt discount		974,000
Amortization of debt issuance costs		294,000
Total interest and amortization expense	$ 0	$ 2,764,000	$ 0	$ 600,000

Debt and Convertible Preferre_7

Debt and Convertible Preferred Stock Warrants - Schedule of Future Minimum Payments Under Notes (Details) $ in Thousands	Sep. 30, 2020USD ($)
Debt Disclosure [Abstract]
Remainder of 2020	$ 2,574
2021	5,175
2022	5,175
2023	5,175
2024	5,175
2025	175,088
Total future payments	198,362
Less amounts representing interest	(25,862)
Total principal amount	$ 172,500

Convertible Preferred Stock a_3

Convertible Preferred Stock and Redeemable Convertible Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 02, 2019	Mar. 31, 2019	Sep. 30, 2019
Temporary Equity [Line Items]
Aggregate gross proceeds			$ 26,283
Initial Public Offering
Temporary Equity [Line Items]
Convertible preferred stock converted into common stock	58,363,606
Series H
Temporary Equity [Line Items]
Redeemable convertible preferred stock issued		6,350,345
Convertible preferred stock issued		3,831,766
Preferred stock par value		$ 6.8748
Aggregate gross proceeds		$ 70,000

Convertible Preferred Stock a_4

Convertible Preferred Stock and Redeemable Convertible Preferred Stock - Summary of Convertible Preferred Stock and Redeemable Convertible Preferred Stock (Details) $ in Thousands	Mar. 31, 2019USD ($)shares
Temporary Equity [Line Items]
Shares Authorized	115,185,867
Shares Issued	114,960,357
Shares Outstanding	114,960,357
Net Carrying Value | $	$ 367,406
Aggregate Liquidation Preference | $	$ 376,007
Series A
Temporary Equity [Line Items]
Shares Authorized	18,960,000
Shares Issued	18,941,619
Shares Outstanding	18,941,619
Net Carrying Value | $	$ 9,161
Aggregate Liquidation Preference | $	$ 9,217
Series B
Temporary Equity [Line Items]
Shares Authorized	13,784,443
Shares Issued	13,652,791
Shares Outstanding	13,652,791
Net Carrying Value | $	$ 13,774
Aggregate Liquidation Preference | $	$ 14,000
Series C
Temporary Equity [Line Items]
Shares Authorized	9,335,659
Shares Issued	9,328,791
Shares Outstanding	9,328,791
Net Carrying Value | $	$ 20,289
Aggregate Liquidation Preference | $	$ 20,374
Series D
Temporary Equity [Line Items]
Shares Authorized	14,367,652
Shares Issued	14,324,642
Shares Outstanding	14,324,642
Net Carrying Value | $	$ 39,886
Aggregate Liquidation Preference | $	$ 40,000
Series E
Temporary Equity [Line Items]
Shares Authorized	13,612,543
Shares Issued	13,586,946
Shares Outstanding	13,586,946
Net Carrying Value | $	$ 39,880
Aggregate Liquidation Preference | $	$ 40,000
Series F
Temporary Equity [Line Items]
Shares Authorized	12,956,724
Shares Issued	12,956,724
Shares Outstanding	12,956,724
Net Carrying Value | $	$ 56,154
Aggregate Liquidation Preference | $	$ 58,397
Series G
Temporary Equity [Line Items]
Shares Authorized	21,986,733
Shares Issued	21,986,733
Shares Outstanding	21,986,733
Net Carrying Value | $	$ 118,325
Aggregate Liquidation Preference | $	$ 123,881
Series H
Temporary Equity [Line Items]
Shares Authorized	10,182,113
Shares Issued	10,182,111
Shares Outstanding	10,182,111
Net Carrying Value | $	$ 69,937
Aggregate Liquidation Preference | $	$ 70,138

Share-based Compensation Plan_2

Share-based Compensation Plans - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2011	Aug. 04, 2020
Selling, General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Compensation expense				$ 0.8
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares issued in transaction	382,477
Sale of stock, price per share	$ 12.72			$ 12.72
Sale of stock, aggregate amount	$ 4.9
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized		1,750,000			1,750,000
Annual increase in number of shares, percentage of shares of outstanding common stock		1.00%			1.00%
Increase in shares available for grant								858,723
Number of shares purchased		0	0		0	0
Unrecognized compensation costs		$ 0.1			$ 0.1
Weighted average period expect to recognized					1 month 6 days
Employee Stock Purchase Plan | First Business Day
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted as percentage on fair value of stock					85.00%
Employee Stock Purchase Plan | Last Business Day
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted as percentage on fair value of stock					85.00%
Maximum | Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual increase in available number of authorized shares		1,750,000			1,750,000
2011 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period							4 years
Percentage of maximum incentive stock options granted to stockholders							10.00%
2011 Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options exercisable period							10 years
2011 Plan | Incentive and Non-statutory Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized							12,987,255
2011 Plan | Incentive and Non-statutory Stock Options | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted as percentage on fair value of stock							100.00%
2011 Plan | Incentive Stock Options | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted as percentage on fair value of stock							110.00%
2019 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized		8,000,000			8,000,000
Annual increase in number of shares, percentage of shares of outstanding common stock		5.00%			5.00%
Increase in shares available for grant								4,293,616
2019 Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual increase in available number of authorized shares		8,000,000			8,000,000

Share-based Compensation Plan_3

Share-based Compensation Plans - Schedule of Total Stock-based Compensation Expense, Excluding Compensation Expense Related to Stock Sales, by Function (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 7,372	$ 2,520	$ 16,911	$ 4,916
Marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	705	145	1,228	287
Operations and Technology
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	2,892	1,098	7,222	2,064
Selling, General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 3,775	$ 1,277	$ 8,461	$ 2,565

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Line Items]
Operating lease costs	$ 6.2		$ 18.4
Variable lease costs	$ 1.1		$ 3.1
Rent expense from operating leases		$ 4.8		$ 13.4
Minimum
Leases [Line Items]
Operating lease term	1 year		1 year
Maximum
Leases [Line Items]
Operating lease term	14 years		14 years

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Operating Lease Liabilities (Details) $ in Thousands	Sep. 30, 2020USD ($)
Leases [Abstract]
Remainder of 2020	$ 5,054
2021	24,205
2022	21,548
2023	20,168
2024	19,759
Thereafter	71,924
Total future minimum payments	162,658
Less: Imputed interest	(35,715)
Present value of operating lease liabilities	$ 126,943

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Lease Payments Under Noncancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2019USD ($)
Leases [Abstract]
2020	$ 20,530
2021	22,059
2022	19,610
2023	18,307
2024	17,957
Thereafter	67,208
Total future minimum payments	$ 165,671

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Cash Flow Information Related to Operating Leases (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Leases [Abstract]
Operating cash flows used for operating leases	$ 6,113
Operating lease assets obtained in exchange for operating lease liabilities	$ 16,671

Leases - Schedule of Weighted A

Leases - Schedule of Weighted Average Remaining Lease Term and Discount Rate For Operating Leases (Details)	Sep. 30, 2020
Leases [Abstract]
Weighted average remaining lease term	7 years 3 months 18 days
Weighted average discount rate	7.00%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	1 Months Ended
	Jan. 31, 2018USD ($)Installment	Sep. 30, 2020USD ($)	Dec. 31, 2019USD ($)
Other Commitments [Line Items]
Outstanding liability		$ 0.5	$ 0.9
Other Accrued and Current Liabilities
Other Commitments [Line Items]
Outstanding liability			0.5
Other Noncurrent Liabilities
Other Commitments [Line Items]
Outstanding liability			$ 0.4
Selling, General and Administrative
Other Commitments [Line Items]
Estimated fair value of grant expense	$ 1.7
Fair value of grant, discount rate	10.00%
Endowment Agreement
Other Commitments [Line Items]
Donation fund	$ 2
Annual installment payment of donation fund	$ 0.5
Number of annual installments | Installment	4

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - Coronavirus Aid, Relief, and Economic Security Act (CARES)	Mar. 27, 2020
Operating Loss Carryforwards [Line Items]
Potential offset percentage of taxable income with NOLs	100.00%
Potential offset of taxable income before act enactment percentage	80.00%
Reduced life for income tax if improvement property capitalized	15 years
Minimum
Operating Loss Carryforwards [Line Items]
Temporarily increases the interest deductibility threshold percentage of adjusted taxable income	30.00%
Maximum
Operating Loss Carryforwards [Line Items]
Temporarily increases the interest deductibility threshold percentage of adjusted taxable income	50.00%
Depreciating costs over for income tax purposes	39 years

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Reconciliation of Numerator and Denominator Used in Calculation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator
Net loss attributable to common stockholders	$ (43,305)	$ (25,274)	$ (124,489)	$ (78,726)
Denominator
Weighted-average common shares outstanding used to calculate net loss per share attributable to common stockholders, basic and diluted	87,869,321	84,634,956	87,176,677	34,556,485
Net loss per share attributable to common stockholders, basic and diluted	$ (0.49)	$ (0.30)	$ (1.43)	$ (2.28)

Net Loss Per Share - Schedule_2

Net Loss Per Share - Schedule of Anti-dilutive Securities Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	20,869,552	9,969,039
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	6,444,997	9,417,490
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	4,625,248	551,549
Employee Stock Purchase Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	93,853
Convertible Senior Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	9,705,454

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended
	Nov. 30, 2020	Sep. 30, 2020
Subsequent Event [Line Items]
Minimum lease payments for the initial lease term		$ 162,658
Scenario Forecast
Subsequent Event [Line Items]
Lessee, operating lease, existence of option to extend	true
Operating lease term expiration date	May 31, 2031
Minimum lease payments for the initial lease term	$ 31,000
Lessee, operating lease, option to extend	option to extend for up to ten years